Certain reclassifications have been made in the consolidated statements of operations to conform data for prior periods to the current format. Beginning with the year ended December 31, 2021, we presented a gross profit subtotal in our consolidated statements of operations, which requires certain depreciation expense and amortization expense to be included within cost of revenue. We believe the presentation of gross profit is preferable as it facilitates investors’ ability to model across our segments and enhances comparability with our public company peers. To effect the presentation of gross profit, we present the amortization expense for certain intangible assets and data acquisition costs within cost of revenue and have reclassified certain amounts in prior periods in the consolidated statements of operations from technology and development expenses to cost of revenue. Additionally, we reclassified the amortization expense for trade names and trademarks and customer relationship intangible assets from technology and development expenses to sales and marketing expenses. This change has no impact on income (loss) from operations or net income (loss).


	Year Ended December 31, 2020						Year Ended December 31, 2019
	As Reported		As Revised		Effect of Change		As Reported		As Revised		Effect of Change
Cost of revenue:
Homes	$	1,621,040	$	1,634,755	$	13,715	$	1,315,345	$	1,324,464	$	9,119
IMT	104,091		193,097		89,006		98,522		193,885		95,363
Mortgages	31,264		38,540		7,276		18,154		25,750		7,596
Total cost of revenue	1,756,395		1,866,392		109,997		1,432,021		1,544,099		112,078
Operating expenses:
Sales and marketing	672,816		691,119		18,303		714,128		728,631		14,503
Technology and development	518,072		390,172		(127,900)		477,347		350,923		(126,424)
General and administrative	357,122		356,722		(400)		366,176		366,019		(157)

The preparation of financial statements in conformity with GAAP requires management to make certain estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and the related disclosures at the date of the financial statements, as well as the reported amounts of revenue and expenses during the periods presented. On an ongoing basis, we evaluate our estimates, including those related to the accounting for certain revenue offerings, the net realizable value of inventory, restructuring costs, amortization period and recoverability of contract cost assets, website and software development costs, recoverability of long-lived assets and intangible assets, share-based compensation, income taxes, business combinations and the recoverability of goodwill, among others. To the extent there are material differences between these estimates, judgments or assumptions and actual results, our financial statements will be affected. The COVID-19 pandemic as well as our plans to wind down Zillow Offers operations have introduced significant additional uncertainty with respect to estimates, judgments and assumptions, which may materially impact the estimates previously listed, among others.

Financial instruments, which potentially subject us to concentrations of credit risk, consist primarily of cash and cash equivalents, investments, accounts receivable and mortgage loans held for sale. We place cash and cash equivalents and investments with major financial institutions, which management assesses to be of high credit quality, in order to limit exposure of our investments.

Credit risk with respect to accounts receivable is dispersed due to the large number of customers. There were no customers that comprised 10% or more of our total accounts receivable as of December 31, 2021 and 2020. Further, our credit risk on accounts receivable is mitigated by the relatively short payment terms that we offer. Collateral is not required for accounts receivable. We maintain an allowance for doubtful accounts such that receivables are stated at net realizable value.

Cash includes demand deposits with banks or financial institutions. Cash equivalents include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Our cash equivalents include only investments with original maturities of three months or less. We regularly maintain cash in excess of federally insured limits at financial institutions.

Our investments consist of fixed income securities, which include U.S. government agency securities, corporate notes and bonds, commercial paper, treasury bills, municipal securities and certificates of deposit, and are classified as available-for-sale securities. The investments are available to support current operations and are classified as short-term investments measured at fair value. Our investment policy only allows for purchases of investment-grade securities and provides guidelines on concentrations to ensure minimum risk of loss. We evaluate whether unrealized losses on available-for-sale debt securities are the result of credit worthiness of the securities held or other non-credit related factors. If an unrealized loss is the result of credit quality factors, we recognize an allowance reflective of our current estimate of credit losses expected to be incurred over the life of the financial instrument on a specific identification basis upon initial recognition and at each reporting period. If a reduction in value is a result of other factors, we continue to classify the losses as a reduction of comprehensive income (loss) unless either we intend to sell the security or it is more likely than not we will be required to sell the security. We did not identify any unrealized loss positions in our available-for-sale securities that were the result of credit losses as of December 31, 2021 or 2020. Additionally, we have the ability to hold to maturity and more likely than not will not be required to sell the securities before a recovery of the amortized cost basis has occurred.

Mortgage loans held for sale include residential mortgages originated for sale in the secondary market in connection with Zillow Home Loans. We have elected the fair value option for all mortgage loans held for sale as election of this option allows for a better offset of the changes in fair values of the loans and the derivative instruments used to economically hedge them without having to apply complex hedge accounting provisions. Mortgage loans held for sale are initially recorded at fair value based on either sale commitments or current market quotes and are adjusted for subsequent changes in fair value until the loans are sold. Net origination costs and fees associated with mortgage loans are recognized as incurred. We sell substantially all of the mortgages we originate and the related servicing rights to third-party purchasers. Interest income is earned from the date a mortgage loan is originated until the loan is sold and is classified within other income in the consolidated statements of operations.

Substantially all of the mortgage loans originated are sold within a short period of time in the secondary mortgage market on a servicing released, nonrecourse basis, which limits exposure to nonperformance by loan buyer counterparties. However, we remain liable for certain limited representations and warranties related to loan sales, such as non-compliance with defined loan origination or documentation standards, including misstatement in the loan documents, early payoff or default on early payments. Mortgage investors could seek to have us buy back loans or compensate them for losses incurred on mortgages we have sold based on claims that we breached our limited representations and warranties. We record a reserve for probable losses in connection with the sale of mortgage loans.

We are party to interest rate lock commitments (“IRLCs”), which are extended to borrowers who have applied for loan funding and meet defined credit and underwriting criteria in connection with our Zillow Home Loans mortgage origination business. IRLCs are accounted for as derivative instruments recorded at fair value with gains and losses recognized in revenue in the consolidated statements of operations. We manage our interest rate risk related to IRLCs and mortgage loans held for sale through the use of derivative instruments, generally forward contracts on mortgage-backed securities (“MBSs”), which are commitments to either purchase or sell a specified financial instrument at a specified future date for a specified price, and mandatory loan commitments, which are an obligation by an investor to buy loans at a specified price within a specified time period. We do not enter into or hold derivatives for trading or speculative purposes, and our derivatives are not designated as hedging instruments. Changes in the fair value of our derivative financial instruments are recognized in revenue in our consolidated statements of operations, and the fair values are reflected in other assets or other liabilities, as applicable. Refer to Note 3 to our consolidated financial statements for additional information regarding IRLCs and related derivatives.

There are no credit-risk-related contingent features within our derivative agreements, and counterparty risk is considered minimal. Gains and losses on IRLCs are substantially offset by corresponding gains or losses on forward contracts on MBSs and mandatory loan commitments. We are generally not exposed to variability in cash flows of derivative instruments for more than approximately 90 days.

Inventory is comprised of homes acquired through Zillow Offers and is stated at the lower of cost or net realizable value. Homes are removed from inventory on a specific identification basis when they are resold. Stated cost includes consideration paid to acquire and update each home including associated allocated overhead costs and holding costs incurred during the renovation period. Work-in-progress inventory includes homes undergoing updates and finished goods inventory includes homes ready for resale. Unallocated overhead costs are expensed as incurred and included in cost of revenue in the consolidated statements of operations. For our Homes segment, selling costs, such as real estate agent commissions, escrow and title fees and staging costs, as well as holding costs incurred during the period that homes are listed for sale, including utilities, taxes and maintenance, are expensed as incurred and classified within sales and marketing expenses in the consolidated statements of operations.

Each quarter we review the value of homes held in inventory for indicators that net realizable value is lower than cost. When evidence exists that the net realizable value of inventory is lower than its cost, the difference is recognized in cost of revenue and the value of the corresponding asset is reduced. Refer to Note 5 to our consolidated financial statements for additional information regarding inventory.

Accounts receivable represent our unconditional right to consideration. Accounts receivable are generally due within 30 days and are recorded net of the allowance for doubtful accounts. We have an allowance for doubtful accounts for our accounts receivable balances, which represents our estimate of expected credit losses over the contractual life of the accounts receivable. To evaluate the adequacy of our allowance for doubtful accounts each reporting period, we analyze the accounts receivable balances with similar risk characteristics on a collective basis, considering factors such as the aging of receivable balances, payment terms, geographic location, historical loss experience, current information and future expectations. Changes to the allowance for doubtful accounts are adjusted through credit loss expense, which is included in general and administrative expenses in the consolidated statements of operations.

Contract assets represent amounts for which we have recognized revenue for contracts that have not yet been invoiced to our customers. Contract assets are primarily related to our Premier Agent Flex and rentals pay per lease offerings, whereby we estimate variable consideration based on the expected number of real estate transactions to be closed for Premier Agent Flex and qualified leases to be secured for rentals pay per lease and recognize revenue when we satisfy our performance obligations under the corresponding contracts. Contract assets are recorded within prepaid expenses and other current assets in our consolidated balance sheets.

Contract liabilities consist of deferred revenue, which relates to payments received in advance of performance under a revenue contract. Deferred revenue is primarily related to prepaid advertising fees received or billed in advance of satisfying our performance obligations and prepaid but unrecognized subscription revenue. Deferred revenue is recognized when or as we satisfy our obligations under contracts with customers.

We capitalize certain incremental costs of obtaining contracts with customers which we expect to recover. These costs relate to commissions paid to sales personnel, primarily for our Premier Agent and Premier Broker programs. As a practical expedient, we recognize the incremental costs of obtaining a contract as an expense when incurred if the amortization period of the asset that we otherwise would have recognized is one year or less. Capitalized commission costs are recorded as contract cost assets in our consolidated balance sheets. Contract cost assets are amortized to expense on a straight-line basis over a period that is consistent with the transfer to the customer of the products or services to which the asset relates, generally the estimated life of the customer relationship. Amortization expense related to contract cost assets is included in sales and marketing expenses in our consolidated statements of operations. In determining the estimated life of our customer relationships, we consider quantitative and qualitative data, including, but not limited to, historical customer data, recent changes or expected changes in product or service offerings and changes in how we monetize our products and services. The amortization period for capitalized contract costs related to our Premier Agent and Premier Broker programs are approximately three years.

We monitor our contract cost assets for impairment and recognize an impairment loss in the consolidated statements of operations to the extent the carrying amount of the asset recognized exceeds the amount of consideration that we expect to receive in the future and that we have received but have not recognized in revenue less the costs that relate directly to providing those goods or services that have not yet been recognized as expenses. Refer to Note 7 of our consolidated financial statements for more information regarding contract cost assets.

As the sponsor of certain securitization transactions for the Zillow Offers business, Zillow Group is required to retain at least a 5% interest in the credit risk of the asset-backed securities issued. The interests are presented as beneficial interests in securitizations in our consolidated balance sheet as of December 31, 2021. These investments are classified as available-for-sale debt securities and are measured at fair value on a recurring basis with unrealized gains and losses reported within our consolidated statements of other comprehensive loss.

The beneficial interests in securitizations accrete interest income over their expected lives using the effective yield method which reflects a portion of the overall fair value adjustment recorded each period on the investments. We reevaluate the cash flow estimates over the lives of the beneficial interests on a quarterly basis to determine if a change to the accretable yield is required on a prospective basis.

Maintenance and repair costs are charged to expense as incurred. Major improvements, which extend the useful life of the related asset, are capitalized. Upon disposal of a fixed asset, we record a gain or loss based on the difference between the proceeds received and the net book value of the disposed asset. We remove fully depreciated property and equipment from the cost and accumulated depreciation amounts disclosed.

The costs incurred in the preliminary stages of website and software development are expensed as incurred. Once an application has reached the development stage, internal and external costs, if direct and incremental and deemed by management to be significant, are capitalized in property and equipment and amortized on a straight-line basis over their estimated useful lives. Maintenance and enhancement costs, including those costs in the post-implementation stages, are typically expensed as incurred, unless such costs relate to substantial upgrades and enhancements to the website or software that result in added functionality, in which case the costs are capitalized and amortized on a straight-line basis over the estimated useful lives. Amortization expense related to capitalized website and software development costs is included in cost of revenue in our consolidated statements of operations.

Capitalized development activities placed in service are amortized over the expected useful lives of those releases, currently estimated at one to five years. The estimated useful lives of website and software development activities are reviewed frequently and adjusted as appropriate to reflect upcoming development activities that may include significant upgrades and/or enhancements to the existing functionality. We remove fully amortized website and software development costs from the cost and accumulated amortization amounts disclosed.

We have lease agreements that include both lease components (e.g., fixed rent) and non-lease components (e.g., common area maintenance). For such leases, we account for the lease and non-lease components as a single component. For leases with an initial term of 12 months or less, we recognize the associated lease payments in the consolidated statements of operations on a straight-line basis over the lease term.

Right of use assets represent our right to use an underlying asset during the lease term and lease liabilities represent our obligation to make lease payments. Right of use assets and lease liabilities are recognized at the lease commencement date based on the present value of the total lease payments not yet paid, including lease incentives not yet received, with the right of use assets further adjusted for any prepaid or accrued lease payments, lease incentives received and/or initial direct costs incurred. Certain lease arrangements also include variable payments for costs such as common-area maintenance, utilities, taxes or other operating costs, which are based on a percentage of actual expenses incurred or a fluctuating rate which is unknown at the inception of the contract. These variable lease payments are excluded from the measurement of the right of use assets and lease liabilities.

Our leases have remaining lease terms ranging from less than one year to eleven years, some of which include options to extend the lease term for up to an additional ten years. For example, our largest leases, which include our corporate headquarters in Seattle, Washington and office space in New York, New York and San Francisco, California, include options to renew the existing leases for either one or two periods of five years. When determining if a renewal option is reasonably certain of being exercised at lease commencement, we consider several factors, including but not limited to, contract-based, asset-based and entity-based factors. We reassess the term of existing leases if there is a significant event or change in circumstances within our control that affects whether we are reasonably certain to exercise an option to extend a lease. Examples of such events or changes include construction of significant leasehold improvements or other modifications or customizations to the underlying asset, relevant business decisions or subleases. As of December 31, 2021, we have concluded that our renewal options are not reasonably certain of being exercised, therefore, renewals are not included in the right of use assets and lease liabilities.

As our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the lease commencement date in determining the present value of the lease payments. We apply a portfolio approach for determining the incremental borrowing rate based on the applicable lease terms and the current economic environment.

From time to time, we may enter into sublease agreements with third parties. Our subleases generally do not relieve us of our primary obligations under the corresponding head lease. As a result, we account for the head lease based on the original assessment at lease inception. We determine if the sublease arrangement is either a sales-type, direct financing, or operating lease at inception of the sublease. If the total remaining lease cost on the head lease for the term of the sublease is greater than the anticipated sublease income, the right of use asset is assessed for impairment. Our subleases are generally operating leases and we recognize sublease income on a straight-line basis over the sublease term.

Goodwill represents the excess of the cost of an acquired business over the fair value of the assets acquired at the date of acquisition, and is not amortized. We assess the impairment of goodwill on an annual basis, in our fourth quarter, or whenever events or changes in circumstances indicate that goodwill may be impaired. In our evaluation of goodwill, we typically first perform a qualitative assessment to determine whether the carrying value of each reporting unit is greater than its fair value. If it is more likely than not that the carrying value of a reporting unit is greater than its fair value, we perform a quantitative assessment and an impairment charge is recorded in our statements of operations for the excess of carrying value of the reporting unit over its fair value. During the years ended December 31, 2021, 2020 and 2019, we did not record any impairments related to goodwill. Refer to Note 10 for additional information related to goodwill.

We purchase and license data content from multiple data providers. This data content consists of United States county data about home details and other information relating to the purchase price of homes, both current and historical, as well as imagery, mapping and parcel data that is displayed on our mobile applications and websites. In some instances, we retain perpetual rights to this information after our contract with a vendor ends; in other instances, the information and data are licensed only during the fixed term of the agreement. Additionally, certain data license agreements provide for uneven payment amounts throughout the contract term.

We capitalize payments made to third parties for data licenses that we expect to recover through generation of revenue and margins. For data license contracts that include uneven payment amounts, we capitalize the payments as they are made as an intangible asset and the total contract value is typically amortized on a straight-line basis over the term of the contract, which is equivalent to the estimated useful life of the asset. The amortization period for the capitalized purchased content is based on our best estimate of the useful life of the asset, which is approximately six years.

Under certain other data agreements, the underlying data is obtained on a subscription basis with consistent monthly or quarterly recurring payment terms over the contractual period. Upon the expiration of such arrangements, we no longer have the right to access the related data, and therefore, the costs incurred under such contracts are not capitalized and are expensed as payments are made.

We also capitalize costs related to the license of certain internal-use software from third parties, including certain licenses of software in cloud computing arrangements. Additionally, we capitalize costs incurred during the application development stage related to the development of internal-use software and enterprise cloud computing services. We expense costs as incurred related to the planning and post-implementation phases of development. Capitalized internal-use software costs are amortized on a straight-line basis over the estimated useful life of the asset, which is currently one to five years.

We also have intangible assets for developed technology, customer relationships, and trade names and trademarks which we recorded in connection with acquisitions. Purchased intangible assets with a determinable economic life are carried at cost less accumulated amortization. These intangible assets are amortized over the estimated useful life of the asset on a straight-line basis.

We evaluate intangible assets and other long-lived assets for impairment whenever events or circumstances indicate that they may not be recoverable. Recoverability is measured by comparing the carrying amount of an asset group to future undiscounted net cash flows expected to be generated. We group assets for purposes of such review at the lowest level for which identifiable cash flows of the asset group are largely independent of the cash flows of the other groups of assets and liabilities. If this comparison indicates impairment, the amount of impairment to be recognized is calculated as the difference between the carrying value and the fair value of the asset group.

Prior to April 2020, our Trulia trade names and trademarks intangible asset had not been amortized, and we assessed the asset for impairment on an annual basis, in our fourth quarter, or whenever events or changes in circumstances indicated that the asset may be impaired. On an interim basis, we considered if there were any events and circumstances that could affect the significant inputs used to determine the fair value of the intangible asset, including, but not limited to, costs that could have a negative effect on future expected earnings and cash flows, changes in certain key performance metrics, and changes in management, key personnel, strategy or customers. In our evaluation of our trade names and trademarks intangible asset, we typically performed a qualitative assessment to determine whether the fair value of the intangible asset was more likely than not impaired. If so, we performed a quantitative assessment and an impairment charge was recorded in our statements of operations for the excess of the carrying value of the intangible asset over its fair value.

We recognize identifiable assets acquired and liabilities assumed at their acquisition date fair values. Goodwill as of the acquisition date is measured as the excess of consideration transferred over the net of the acquisition date fair values of the assets acquired and the liabilities assumed. While we use our best estimates and assumptions for the purchase price allocation process to value assets acquired and liabilities assumed at the acquisition date, our estimates are inherently uncertain and subject to refinement. As a result, during the measurement period, which may be up to one year from the acquisition date, we record adjustments to the assets acquired and liabilities assumed, with the corresponding offset to goodwill to the extent that we identify adjustments to the preliminary purchase price allocation. Upon the conclusion of the measurement period or final determination of the values of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are recorded to our consolidated statements of operations. We recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined.

We do not disclose the transaction price related to remaining performance obligations for (i) contracts with an original expected duration of one year or less and (ii) contracts for which we recognize revenue at the amount to which we have the right to invoice for performance completed to date. The remaining duration over which we satisfy our performance obligations is generally less than one year.

Zillow Offers Revenue. Zillow Offers revenue is derived from the resale of homes. We recognize revenue at the time of the closing of the home sale when title to and possession of the property are transferred to the buyer. The amount of revenue recognized for each home sale is equal to the full sales price of the home net of resale concessions and credits to the buyer and does not reflect real estate agent commissions, closing or other costs associated with the transaction.

Other Revenue. Other Homes revenue is primarily generated through Zillow Closing Services, which offers title and escrow services to home buyers and sellers, including title search procedures for title insurance policies, escrow and other closing services. Title insurance, which is recorded net of amounts remitted to third-party underwriters, and title and escrow closing fees, are recognized as revenue upon closing of the underlying real estate transaction.

Premier Agent Revenue. Premier Agent revenue is derived from our Premier Agent and Premier Broker programs. Our Premier Agent and Premier Broker programs offer a suite of marketing and business technology products and services to help real estate agents and brokers achieve their advertising goals while growing and managing their businesses and brands. All Premier Agents and Premier Brokers receive access to a dashboard portal on our mobile application and website that provides individualized program performance analytics, our customer relationship management, or CRM, tool that captures detailed information about each contact made with a Premier Agent or Premier Broker through our mobile and web platforms and our account management tools. The marketing and business technology products and services promised to Premier Agents and Premier Brokers are delivered over time, as the customer simultaneously receives and consumes the benefit of the performance obligations.

Premier Agent and Premier Broker advertising products, which include the delivery of validated consumer connections, or leads, are primarily offered on a share of voice basis. Payment is received prior to the delivery of connections. Connections are delivered when consumer contact information is provided to Premier Agents and Premier Brokers. We do not promise any minimum or maximum number of connections to customers, but instead control when and how many connections to deliver based on a customer’s share of voice. We determine the number of connections to deliver to Premier Agents and Premier Brokers in each zip code using a market-based pricing method in consideration of the total amount spent by Premier Agents and Premier Brokers to purchase connections in the zip code during the month. This results in the delivery of connections over time in proportion to each Premier Agent’s and Premier Broker’s share of voice. A Premier Agent’s or Premier Broker’s share of voice in a zip code is determined by their proportional monthly prepaid spend in that zip code as a percentage of the total monthly prepaid spend of all Premier Agents and Premier Brokers in that zip code, and determines the proportion of consumer connections a Premier Agent or Premier Broker receives. The number of connections delivered for a given spend level is dynamic - as demand for advertising in a zip code increases or decreases, the number of connections delivered to a Premier Agent or Premier Broker in that zip code decreases or increases accordingly.

We primarily recognize revenue related to the Premier Agent and Premier Broker products and services based on the monthly prepaid spend recognized on a straight-line basis during the monthly billing period over which the products and services are provided. This methodology best depicts how we satisfy our performance obligations to customers, as we continuously transfer control of the performance obligations to the customer over time. Given a Premier Agent or Premier Broker typically prepays their monthly spend and the monthly spend is refunded on a pro-rata basis upon cancellation of the contract by a customer, we have determined that Premier Agent and Premier Broker contracts are effectively daily contracts, and each performance obligation is satisfied over time as each day lapses. We have not allocated the transaction price to each performance obligation within our Premier Agent and Premier Broker arrangements, as the amounts recognized would be the same irrespective of any allocation.

We also offer a pay for performance pricing model called “Flex” for Premier Agent and Premier Broker advertising services in certain markets. Flex is available to select partners alongside our legacy market-based pricing model. With the Flex model, Premier Agents and Premier Brokers are provided with validated leads at no initial cost and pay a performance advertising fee only when a real estate transaction is closed with one of the leads. With this pricing model, the transaction price represents variable consideration, as the amount to which we expect to be entitled varies based on the number of validated leads that convert into real estate transactions and the value of those transactions. Beginning in the third quarter of 2020, we believe we have sufficient historical data available and therefore estimate variable consideration and record revenue as performance obligations, or validated leads, are transferred. We do not believe that a significant reversal in the amount of cumulative revenue recognized will occur once the uncertainty related to the number of transactions closed is subsequently resolved. We record a corresponding contract asset for the estimate of variable consideration for Flex when the right to the consideration is conditional. When the right to consideration becomes unconditional, we reclassify amounts to accounts receivable. Contract assets are included within prepaid expenses and other current assets within our consolidated balance sheets. Refer to Note 6 of our consolidated financial statements for further details regarding our contract assets. Prior to the third quarter of 2020, we recognized revenue for validated leads when we received payment for a real estate transaction closed with a Flex lead.

Other Revenue. Other IMT revenue primarily includes revenue generated by rentals, new construction, display and ShowingTime, as well as revenue from the sale of various other marketing and business products and services to real estate professionals. Rentals revenue includes the sale of advertising and a suite of tools to rental professionals, landlords and other market participants. Rentals revenue primarily includes revenue generated by advertising sold to property managers, landlords and other rental professionals on a cost per lead, click, lease, listing or impression basis or for a fixed fee for certain advertising packages. Rentals revenue also includes revenue generated from our rental applications product, through which potential renters can submit applications to multiple properties for a flat service fee. We recognize revenue as leads, clicks and impressions are provided to rental professionals, or as rental listings are published on our mobile applications and websites, which is the amount for which we have the right to invoice. We recognize revenue related to our fixed fee rentals product on a straight-line basis over the contract term as the performance obligations, rental listings on our mobile applications and websites, are satisfied over time based on time elapsed. The number of leases generated through our rentals pay per lease product during the period is accounted for as variable consideration, and we estimate the amount of variable consideration based on the expected number of qualified leases secured during the period. We do not believe that a significant reversal in the amount of cumulative revenue recognized will occur once the uncertainty related to the number of leases secured is subsequently resolved.

Rentals revenue also includes revenue generated from our rental applications product through which potential renters can submit applications to multiple rental properties over a 30-day period for a flat service fee. We recognize revenue for the rental applications product on a straight-line basis during the contractual period over which the customer has the right to access and submit the rental application.

Our new construction marketing solutions allow home builders to showcase their available inventory to home shoppers. New construction revenue primarily includes revenue generated by advertising sold to builders on a cost per residential community basis whereby we recognize revenue on a straight-line basis during the contractual period over which the communities are advertised on our mobile applications and websites. New construction revenue also includes revenue generated on a cost per impression basis whereby we recognize revenue as impressions are delivered to users interacting with our mobile applications and websites, which is the amount for which we have the right to invoice. Consideration for new construction products is billed in arrears.

Display revenue primarily consists of graphical mobile and web advertising sold on a cost per thousand impressions or cost per click basis to advertisers promoting their brands on our mobile applications and websites. We recognize display revenue as clicks occur or as impressions are delivered to users interacting with our mobile applications or websites, which is the amount for which we have the right to invoice.

ShowingTime revenue is primarily generated by Appointment Center, a software-as-a-service and call center solution allowing real estate agents, brokerages and multiple listing services to efficiently schedule real estate viewing appointments on behalf of their customers. Appointment Center revenue is primarily billed in advance on a monthly basis and recognized ratably over the contract period which aligns to our satisfaction of performance obligations.

Mortgage origination revenue recorded within our Mortgages segment reflects origination fees on purchase or refinance mortgages and the corresponding sale, or expected future sale, of a loan. When an IRLC is made to a customer, we record the expected gain on sale of the mortgage, plus the estimated earnings from the expected sale of the associated servicing rights, adjusted for a pull-through percentage (which is defined as the likelihood that an interest rate lock commitment will be originated), as revenue. Revenue from loan origination fees is recognized at the time the related purchase or refinance transactions are completed, usually upon the close of escrow and when we fund the purchase or refinance mortgage loans. Once funded, mortgage loans held for sale are recorded at fair value based on either sale commitments or current market quotes and are adjusted for subsequent changes in fair value until the loan is sold. Origination costs associated with originating mortgage loans are recognized as incurred. We sell substantially all of the mortgages we originate and the related servicing rights to third-party purchasers.

Mortgage loans are sold with limited recourse provisions, which can result in repurchases of loans previously sold to investors or payments to reimburse investors for loan losses. Based on historical experience, discussions with our mortgage purchasers, analysis of the volume of mortgages we originated and current housing and credit market conditions, we estimate and record a loss reserve for mortgage loans held in our portfolio and mortgage loans held for sale, as well as known and projected mortgage loan repurchase requests. These have historically not been significant to our financial statements.

Zillow Group operates Custom Quote and Connect through its wholly owned subsidiary, Zillow Group Marketplace, Inc., a licensed mortgage broker. For our Connect and Custom Quote cost per lead marketing products, participating qualified mortgage professionals typically make a prepayment to gain access to consumers interested in connecting with mortgage professionals. Mortgage professionals who exhaust their initial prepayment prepay additional funds to continue to participate in the marketplace. In Zillow Group’s Connect platform, consumers answer a series of questions to find a local lender, and mortgage professionals receive consumer contact information, or leads, when the consumer chooses to share their information with a lender. Consumers who request rates for mortgage loans in Custom Quotes are presented with customized quotes from participating mortgage professionals. For our cost per lead mortgages products, we recognize revenue when a user contacts a mortgage professional through our mortgages platform, which is the amount for which we have the right to invoice.

Cost of Revenue. Our cost of revenue consists of expenses related to operating our mobile applications and websites, including associated headcount-related expenses, such as salaries, benefits, bonuses and share-based compensation expense, as well as revenue-sharing costs related to our commercial business relationships, depreciation expense and costs associated with hosting our mobile applications and websites. Cost of revenue also includes amortization costs related to capitalized website and development activities, amortization of software, amortization of certain intangible assets and other costs to obtain data used to populate our mobile applications and websites, and amortization of certain intangible assets recorded in connection with acquisitions, including developed technology. For our Homes segment, cost of revenue also consists of the consideration paid to acquire and make certain repairs and updates to each home, including associated overhead costs, as well as inventory valuation adjustments. For our IMT and Mortgages segments, cost of revenue also includes credit card fees and ad serving costs paid to third parties. For our Mortgages segment, cost of revenue also consists of direct costs to originate loans, including underwriting and processing costs.

Sales and Marketing. Sales and marketing expenses consist of advertising costs and other sales expenses related to promotional and marketing activities, headcount-related expenses, including salaries, commissions, benefits, bonuses and share-based compensation expense for sales, sales support, customer support, including the customer connections team, marketing and public relations employees, depreciation expense, and amortization of certain intangible assets recorded in connection with acquisitions, including trade names and trademarks and customer relationships. For our Homes segment, sales and marketing expenses also consist of selling costs, such as real estate agent commissions, escrow and title fees, and staging costs, as well as holding costs incurred during the period that homes are listed for sale, including utilities, taxes and maintenance. Sales and marketing expenses for the Homes segment include $62.3 million and $11.3 million in holding costs for the years ended December 31, 2021 and 2020, respectively. During the year ended December 31, 2020, Homes segment sales and marketing expenses also include certain expenses attributable to our efforts to pause home buying in response to the COVID-19 pandemic. For our Mortgages segment, sales and marketing expenses include headcount-related expenses for loan officers and specialists supporting Zillow Home Loans.

Technology and Development. Technology and development expenses consist of headcount-related expenses, including salaries, benefits, bonuses and share-based compensation expense for individuals engaged in the design, development and testing of our products, mobile applications and websites and the tools and applications that support our products. Technology and development expenses also include equipment and maintenance costs and depreciation expense.

We use the Black-Scholes-Merton option-pricing model to determine the fair value for option awards. In valuing our option awards, we make assumptions about risk-free interest rates, dividend yields, volatility and weighted-average expected lives. We account for forfeitures as they occur. Risk-free interest rates are derived from U.S. Treasury securities as of the option award grant date. Expected dividend yield is based on our historical cash dividend payments, which have been zero to date. The expected volatility for our Class A common stock and Class C capital stock is estimated using our historical volatility. The weighted-average expected life of the option awards is estimated based on our historical exercise data.

Restructuring Costs. The main components of our restructuring plan recorded within impairment and restructuring costs in our consolidated statement of operations for our wind down of Zillow Offers operations relate to employee termination costs, contract termination costs, and charges related to the write-off of assets pertaining to Zillow Offers. One-time employee termination benefits are recognized when the plan of termination has been communicated to employees and certain other criteria are met. Other severance and employee costs, primarily pertaining to ongoing employee benefit arrangements, are recognized when it is probable that the employees are entitled to the severance benefits and the amounts can be reasonably estimated. Contract termination costs are recognized when a contract is terminated in accordance with its terms or at the cease-use date. Asset write-offs are recognized upon their cease-use date. The cumulative effect of a change resulting from a revision to either the timing or the amount of estimated cash flows for restructuring is recognized as an adjustment to the liability in the period of the change. See Note 22 for additional information.

We use the asset and liability approach for accounting and reporting income taxes, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial statement and tax bases of assets and liabilities at the applicable enacted tax rates. A valuation allowance against deferred tax assets would be established if, based on the weight of available evidence, it is more likely than not (a likelihood of more than 50%) that some or all of the deferred tax assets are not expected to be realized.

We establish reserves for tax-related uncertainties based on estimates of whether, and the extent to which, additional taxes will be due. We adjust these reserves in light of changing facts and circumstances, such as the closing of a tax audit, new tax legislation or the change of an estimate. To the extent that the final tax outcome of these matters is different than the amounts recorded, such differences will affect the provision for income taxes in the period in which such determination is made. Interest and penalties related to unrecognized tax benefits are recorded as income tax expense.

In December 2019, the Financial Accounting Standards Board (“FASB”) issued guidance which is intended to simplify the accounting for income taxes. It removes certain exceptions to the general principles and clarifies and amends existing guidance to improve consistent application. This guidance is effective for interim and annual periods beginning after December 15, 2020, and early adoption is permitted. We adopted this guidance on January 1, 2021. The method of adoption for this guidance varies based on the amendment, however, the relevant amendments have been applied on a prospective basis. The adoption of this guidance did not have a material impact on our financial position, results of operations or cash flows.

In October 2021, the FASB issued guidance which requires contract assets and contract liabilities acquired in a business combination to be recognized and measured in accordance with ASC 606, Revenue from Contracts with Customers. We currently recognize contract assets and contract liabilities at the acquisition date based on fair value estimates, which historically has resulted in a reduction to unearned revenue on the balance sheet, and therefore, a reduction to revenue that would have otherwise been recorded as an independent entity. The guidance is effective for interim and annual periods beginning after December 15, 2022 on a prospective basis, with early adoption permitted. We expect to adopt the guidance on January 1, 2023. We are currently evaluating the potential impact of the guidance on our financial position, results of operations and cash flows.

In August 2020, the FASB issued guidance which simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts in an entity’s own equity. Among other changes, the guidance removes the liability and equity separation models for convertible instruments. Instead, entities will account for convertible debt instruments wholly as debt unless convertible instruments contain features that require bifurcation as a derivative or that result in substantial premiums accounted for as paid-in capital. The guidance also requires the application of the if-converted method to calculate the impact of convertible instruments on diluted earnings per share. The guidance is effective for fiscal years beginning after December 15, 2021, with early adoption permitted for fiscal years beginning after December 15, 2020, and can be adopted on either a retrospective or modified retrospective basis. We adopted this guidance on January 1, 2022 using the modified retrospective approach. Upon adoption, we expect to recognize a decrease to additional paid-in capital of $492.5 million, an increase to long-term debt and a cumulative-effect adjustment to accumulated deficit. Additionally, we expect total remaining interest expense over the contractual terms of our convertible senior notes to decrease after adoption of this guidance.