Summary of Significant Accounting Policies

Business Description

Align Technology, Inc. (“We”, “Our”, or “Align”) was incorporated in April 1997 in Delaware and focuses on designing, manufacturing and marketing innovative, technology-rich products to help dental professionals achieve the clinical results they expect and deliver effective, convenient cutting-edge dental treatment options to their patients. We are headquartered in San Jose, California with offices worldwide. Our international headquarters are located in Amsterdam, the Netherlands. We have two operating segments, (1) Clear Aligner, known as the Invisalign System, and (2) Scanners and Services ("Scanner"), known as the iTero intra-oral scanner and OrthoCAD services.

Basis of presentation and preparation

The consolidated financial statements include the accounts of Align and our wholly-owned subsidiaries after elimination of intercompany transactions and balances.

In connection with the preparation of the consolidated financial statements, we evaluated events subsequent to the balance sheet date through the financial statement issuance date and determined that all material transactions have been recorded and disclosed properly.

Out of period adjustment

In 2013, we recorded an out of period correction that resulted in decreases in cost of net revenues of approximately $1.7 million and operating expense of $0.7 million offset in part by an increase in the provision for income taxes of $0.5 million. We do not believe the increase of $1.9 million to net income related to the out of period adjustment is material to the consolidated financial statements for the fiscal year ended December 31, 2013 or to any prior years' consolidated financial statements.

In 2014, we recorded an out of period correction that resulted in an increase in the provision for income taxes of $1.8 million. We do not believe the decrease to net income related to the out of period adjustment is material to the consolidated financial statements for the fiscal year ended December 31, 2014 or to any prior years' consolidated financial statements.

Use of estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“U.S.”) requires our management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ materially from those estimates. On an ongoing basis, we evaluate our estimates, including those related to the fair values of financial instruments, intangible assets and goodwill, useful lives of intangible assets and property and equipment, stock-based compensation, revenue recognition, income taxes, and contingent liabilities, among others. We base our estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities.

Fair value of financial instruments

The carrying amounts of our cash, accounts receivable, accounts payable and other current liabilities approximate their fair value.

We measure our cash equivalents, marketable securities, and our Israeli severance fund at fair value. Fair value is the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. Fair value is estimated by applying the following hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement:

Level 1— Quoted (unadjusted) prices in active markets for identical assets or liabilities.

Level 2— Observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets or liabilities in active markets; quoted prices for identical or similar assets or liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the asset or liability.

Level 3 – Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability.

Cash and cash equivalents

We consider currency on hand, demand deposits, time deposits, and all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash and cash equivalents. Cash and cash equivalents are held in various financial institutions in the U.S. and internationally.

Restricted cash

Our restricted cash balance as of December 31, 2015 was $3.5 million, of which $3.3 million was classified as a long term asset and $0.2 million as a current asset. Our restricted cash balance as of December 31, 2014 was $3.8 million, of which $3.6 million was classified as a long term asset and $0.2 million as a current asset. The restricted cash primarily consisted of funds reserved for legal requirements.

Marketable securities

We invest primarily in money market funds, commercial paper, corporate bonds, U.S. government agency bonds, asset-backed securities, municipal securities, U.S. dollar dominated foreign corporate bonds, U.S. government treasury bonds and certificates of deposits.

Marketable securities are classified as available-for-sale and are carried at fair value. Marketable securities classified as current assets have maturities of less than one year. Unrealized gains or losses on such securities are included in accumulated other comprehensive income, net in stockholders’ equity. Realized gains and losses from maturities of all such securities are reported in earnings and computed using the specific identification cost method. Realized gains or losses and charges for other-than-temporary declines in value, if any, on available-for-sale securities are reported in Interest and other income (expense), net as incurred. We periodically evaluate these investments for other-than-temporary impairment.

Derivative Financial Instruments

In September 2015, we began entering into foreign currency forward contracts to minimize the short-term impact of foreign currency exchange rate fluctuations on cash and certain trade and intercompany receivables and payables. These forward contracts are not designated as hedging instruments and do not subject us to material balance sheet risk due to fluctuations in foreign currency exchange rates. The gains and losses on these forward contracts are intended to offset the gains and losses in the underlying foreign currency denominated monetary assets and liabilities being economically hedged. We do not enter into foreign currency forward contracts for trading or speculative purposes. These instruments are marked to market through earnings every period and generally are one month in original maturity. The net gain or loss from the settlement of these foreign currency forward contracts is recorded in Interest and other income (expense), net in the Consolidated Statements of Operations.

Foreign currency

For our international subsidiaries where the U.S. dollar is the functional currency, we analyze on an annual basis or more often if necessary, if a significant change in facts and circumstances indicate that the primary economic currency has changed. Adjustments from translating certain European and Asia Pacific subsidiaries’ financial statements from the local currency to the U.S. dollar are recorded as a separate component of accumulated other comprehensive income (loss), net in the stockholders’ equity section of the Consolidated Balance Sheet. This foreign currency translation adjustment reflects the translation of the balance sheet at period end exchange rates, and the income statement at an average exchange rate in effect during the period. As of December 31, 2015 and 2014, there were no material amounts in accumulated other comprehensive income, net related to the translation of our foreign subsidiaries’ financial statements.

Some of our international entities operate in a U.S. dollar functional currency environment, and therefore, the foreign currency assets and liabilities are remeasured into the U.S. dollar at current exchange rates except for non-monetary assets and liabilities which are remeasured at historical exchange rates. Revenues and expenses are generally remeasured at an average exchange rate in effect during each period. Gains or losses from foreign currency remeasurement are included in Interest and other income (expense), net. For the year ended December 31, 2015 and 2014, we had foreign currency net losses of $4.0 million and $3.8 million.

Certain risks and uncertainties

Our operating results depend to a significant extent on our ability to market and develop our products. The life cycles of our products are difficult to estimate due, in part, to the effect of future product enhancements and competition. Our inability to successfully develop and market our products as a result of competition or other factors would have a material adverse effect on our business, financial condition and results of operations.

Our cash and investments are held primarily by two financial institutions. Financial instruments which potentially expose us to concentrations of credit risk consist primarily of cash equivalents, marketable securities and accounts receivable. We invest excess cash primarily in money market funds of major financial institutions, U.S. government agencies, U.S. dollar dominated foreign corporate bonds and domestic corporate bonds. If the carrying value of our investments exceeds the fair value, and the decline in fair value is deemed to be other-than-temporary, we will be required to write down the value of our investments, which could materially harm our results of operations and financial condition. Moreover, the performance of certain securities in our investment portfolio correlates with the credit condition of the U.S. economy. We provide credit to customers in the normal course of business. Collateral is not required for accounts receivable, but ongoing evaluations of customers’ credit worthiness are performed. We maintain reserves for potential credit losses and such losses have been within management’s expectations. No individual customer accounted for 10% or more of our accounts receivable at December 31, 2015 or 2014, or net revenues for the year ended December 31, 2015, 2014, or 2013.

In the U.S., the Food and Drug Administration (“FDA”) regulates the design, manufacture, distribution, pre-clinical and clinical study, clearance and approval of medical devices. Products developed by us may require approvals or clearances from the FDA or other international regulatory agencies prior to commercialized sales. There can be no assurance that our products will receive any of the required approvals or clearances. If we were denied approval or clearance or such approval was delayed, it may have a material adverse impact on us.

We have manufacturing operations located outside the U.S. We currently rely on our manufacturing facility in Costa Rica to prepare digital treatment plans using a sophisticated, internally developed computer-modeling program. In addition, we manufacture our clear aligners and distribute our intra-oral scanners at our facility in Juarez, Mexico, and we produce our handheld scanner wand in Or Yehuda, Israel. Our reliance on international operations exposes us to related risks and uncertainties, including difficulties in staffing and managing international operations such as hiring and retaining qualified personnel; controlling production volume and quality of manufacture; political, social and economic instability, particularly as a result of increased levels of violence in Juarez, Mexico and Or Yehuda, Israel; interruptions and limitations in telecommunication services; product and material transportation delays or disruption; trade restrictions and changes in tariffs; import and export license requirements and restrictions; fluctuations in foreign currency exchange rates; and potential adverse tax consequences. If any of these risks materialize, our international manufacturing operations, as well as our operating results, may be harmed.

We purchase certain inventory from sole suppliers. Additionally, we rely on a limited number of hardware manufacturers. The inability of any supplier or manufacturer to fulfill our supply requirements could materially and adversely impact our future operating results.

Inventories

Inventories are valued at the lower of cost or market, with cost computed using either standard cost, which approximates actual cost, or average cost on a first-in-first-out basis. Excess and obsolete inventories are determined primarily based on future demand forecasts, and write-downs of excess and obsolete inventories are recorded as a component of cost of revenues.

Property, plant and equipment

Property, plant and equipment are stated at historical cost less accumulated depreciation and amortization. Depreciation and amortization are computed using the straight-line method over the estimated useful lives of the assets, generally three to ten years. We amortize leasehold improvements over the shorter of the remaining lease term or the estimated useful lives of the assets. We depreciate buildings over periods up to 20 years. Land is not depreciated. Construction in progress ("CIP") is related to the construction or development of property (including land) and equipment that have not yet been placed in service for their intended use. Upon sale or retirement, the asset’s cost and related accumulated depreciation are removed from the general ledger and any related gains or losses are reflected in expenses. Maintenance and repairs are expensed as incurred.

Goodwill and finite-lived acquired intangible assets

Goodwill represents the excess of the purchase price paid over the fair value of tangible and identifiable intangible net assets acquired in business combinations and is allocated to the respective reporting units based on relative synergies generated.

Our intangible assets primarily consist of intangible assets acquired as part of the Cadent acquisition. These assets are amortized using the straight-line method over their estimated useful lives ranging from one to fifteen years, reflecting the period in which the economic benefits of the assets are expected to be realized.

Impairment of goodwill and long-lived assets

Goodwill

We evaluate goodwill for impairment at least annually on November 30th or more frequently if indicators are present, an event occurs or circumstances changes that suggest an impairment may exist and that it would more likely than not reduce the fair value of a reporting unit below its carrying amount. The allocation of goodwill to the respective reporting unit is based on relative synergies generated as a result of an acquisition.

We perform an initial assessment of qualitative factors to determine whether the existence of events and circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. In performing the qualitative assessment, we identify and consider the significance of relevant key factors, events, and circumstances that affect the fair value of our reporting units. These factors include external factors such as macroeconomic, industry, and market conditions, as well as entity-specific factors, such as our actual and planned financial performance. We also give consideration to the difference between the reporting unit fair value and carrying value as of the most recent date a fair value measurement was performed. If, after assessing the totality of relevant events and circumstances, we determine that it is more likely than not that the fair value of the reporting unit exceeds its carrying value and there is no indication of impairment, no further testing is performed; however, if we conclude otherwise, the first step of the two-step impairment test is performed by estimating the fair value of the reporting unit and comparing it with its carrying value, including goodwill.

Step one of the goodwill impairment test consists of a comparison of the fair value of a reporting unit against its carrying amount, including the goodwill allocated to each reporting unit. We determine the fair value of our reporting units based on the present value of estimated future cash flows under the income approach of the reporting units as well as various price or market multiples applied to the reporting unit's operating results along with the appropriate control premium under the marketing approach, both of which are classified as level 3 within the fair value hierarchy (as described in Note 2). If the carrying amount of the reporting unit is in excess of its fair value, step two requires the comparison of the implied fair value of the reporting unit’s goodwill against the carrying amount of the reporting unit’s goodwill. Any excess of the carrying value of the reporting unit’s goodwill over the implied fair value of the reporting unit’s goodwill is recorded as an impairment loss.

Finite-lived intangible assets and long-lived assets

We evaluate long-lived assets (including finite-lived intangible assets) for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset group may not be recoverable. An asset or asset group is considered impaired if its carrying amount exceeds the future undiscounted net cash flows the asset or asset group is expected to generate. Factors we consider important which could trigger an impairment review include significant negative industry or economic trends, significant loss of customers and changes in the competitive environment. If an asset or asset group is considered to be impaired, the impairment to be recognized is calculated as the amount by which the carrying amount of the asset or asset group exceeds its fair market value. Our estimates of future cash flows attributable to our long-lived assets require significant judgment based on our historical and anticipated results and are subject to many assumptions. The estimation of fair value utilizing a discounted cashflow ("DCF") approach includes numerous uncertainties which require our significant judgment when making assumptions of expected growth rates and the selection of discount rates, as well as assumptions regarding general economic and business conditions, and the structure that would yield the highest economic value, among other factors. Refer to Note 5 for details of the impairment analysis.

There were no further triggering events in 2015 that would cause further impairments of our long-lived assets.

Development costs for internal use software

Internally developed software includes enterprise-level business software that we are customizing to meet our specific operational needs. Such capitalized costs include external direct costs utilized in developing or obtaining the applications and payroll and payroll-related costs for employees, who are directly associated with the development of the applications. In 2014, we started an ERP project which we have capitalized $25.4 million of costs as of December 31, 2015 which is included in construction in progress ("CIP"). When the ERP is placed into production, these costs will be amortized over 10 years.

The costs to develop software that is marketed externally have not been capitalized as we believe our current software development process is essentially completed concurrent with the establishment of technological feasibility. As such, all related software development costs are expensed as incurred and included in research and development expense in our Consolidated Statement of Operations.

Product Warranty

Clear Aligner

We warrant our Invisalign products against material defects until the Invisalign case is complete. We accrue for warranty costs in cost of net revenues upon shipment of products. The amount of accrued estimated warranty costs is primarily based on historical experience as to product failures as well as current information on replacement costs. Actual warranty costs could differ materially from the estimated amounts. We regularly review the accrued balances and update these balances based on historical warranty cost trends.

Scanners and Services

We warrant our intra-oral scanners for a period of one year, which include materials and labor. We accrue for these warranty costs based on average historical repair costs. An extended warranty may be purchased for additional fees.

Allowance for Doubtful Accounts and Returns

We maintain allowances for doubtful accounts, for customers that are not able to make payments, and for sales returns. We periodically review these allowances, including an analysis of the customers’ payment history and information regarding the customers’ creditworthiness, as well as historical sales returns as a percentage of revenue. Actual write-offs have not materially differed from the estimated allowance.

Revenue Recognition

We measure and allocate revenue according to the accounting guidance for multiple-deliverable revenue arrangements in Accounting Standards Update (“ASU”) 2009-13, Multiple-Deliverable Revenue Arrangements-a consensus of the Financial Accounting Standard Board (“FASB”) Emerging Issues Task Force.

Multiple-Element Arrangements (“MEAs”): Arrangements with customers may include multiple deliverables, including any combination of products/equipment and services. The deliverables included in the MEAs are separated into more than one unit of accounting when (i) the delivered product/equipment has value to the customer on a stand-alone basis, and (ii) delivery of the undelivered service element(s) is probable and substantially in our control. Arrangement consideration is then allocated to each unit, delivered or undelivered, based on the relative selling price of each unit of accounting based first on vendor-specific objective evidence (“VSOE”) if it exists, second on third-party evidence (“TPE”) if it exists, or on best estimated selling price (“BESP”) if neither VSOE or TPE exist.


•	VSOE - In most instances, this applies to products and services that are sold separately in stand-alone arrangements. We determine VSOE based on pricing and discounting practices for the specific product or service when sold separately, considering geographical, customer, and other economic or marketing variables, as well as renewal rates or stand-alone prices for the service element(s).


•	TPE - If we cannot establish VSOE of selling price for a specific product or service included in a multiple-element arrangement, we use third-party evidence of selling price. We determine TPE based on sales of comparable amount of similar products or service offered by multiple third parties considering the degree of customization and similarity of product or service sold.

•

BESP - The best estimated selling price represents the price at which we would sell a product or service if it were sold on a stand-alone basis. When VSOE or TPE do not exist for all elements, we determine BESP for the arrangement element based on sales, cost and margin analysis, as well as other inputs based on our pricing practices. Adjustments for other market and Company-specific factors are made as deemed necessary in determining BESP. We regularly review our estimates of selling price and maintain internal controls over the establishment and update of these estimates.

Revenue is recognized when persuasive evidence of the arrangement exists, the price is fixed or determinable, collectability is reasonably assured, title and risk of loss has passed to customers based on the shipping terms, and allowances for discounts, returns, and customer incentives can be reliably estimated. Provisions for discounts and rebates to customers are provided for in the same period that the related product sales are recorded.

Clear Aligner

We enter into arrangements (“treatment plans”) that involve multiple future product deliverables. Invisalign Full, Invisalign Teen, and Invisalign Assist products include optional Additional Aligners at no charge for a period of up to five years after initial shipment. Invisalign Teen also includes up to six optional replacement aligners in the price of the product and may be ordered by the dental professional any time throughout treatment. Invisalign Lite includes one optional case refinement in the price of the product. Case refinement is a finishing tool used to adjust a patient's teeth to the desired final position and may be elected by the dental professional at any time during treatment, however, it is generally ordered in the last stages of orthodontic treatment.

We determined that our treatment plans, except Invisalign Assist with progress tracking, comprise the following deliverables which also represent separate units of accounting: single-batched aligners, additional aligners, case refinement, and replacement aligners. We allocate revenue for each treatment plan based on each unit's relative selling price based on BESP and recognize the revenue upon the delivery of each unit in the treatment plan.

For Invisalign Assist with the progress tracking feature, aligners and services are provided to the dental professional every nine stages (“a batch”). We are able to reliably estimate the number of batches which are expected to be shipped for each case based upon our historical experience. The amounts allocated to this deliverable are recognized on a prorated basis as each batch is shipped.

Scanners and Services

We recognize revenues from the sales of iTero intra-oral scanners and CAD/CAM services. CAD/CAM services include scanning services, extended warranty for the intra-oral scanners, a range of iTero restorative services, and OrthoCAD services such as OrthoCAD iRecord. We sell intra-oral scanners and services through both our direct sales force and distribution partners. The intra-oral scanner sales price includes one year of warranty, and for additional fees, the customer may select an unlimited scanning service agreement over a fixed period of time or extended warranty periods. When intra-oral scanners are sold with either an unlimited scanning service agreement and/or extended warranty, we allocate revenue based on each element's relative selling price. We estimate the selling price of each element, as if it is sold on a stand-alone basis, taking into consideration historical prices as well as our discounting strategies.

Scanner revenue, net of related discounts and allowances, is recognized when products or equipment have been shipped and no significant obligations for installation or training remain. For certain distributors who provide installation and training to the customer, we recognize scanner revenue when the intra-oral scanner is shipped to the distributor assuming all of the other revenue recognition criteria have been met. Discounts are deducted from revenue at the time of sale. Returns of products, excluding warranty related returns, are infrequent and insignificant.

Service revenue, including iTero restorative and all OrthoCAD services are recognized upon delivery or ratably over the contract term as the specified services are performed. If a customer selects a pay per use basis for scanning service fees, the revenue is recognized as the service is provided.

We offer customers an option to purchase extended warranties on certain products. We recognize revenue on these extended warranty contracts ratably over the life of the contract. The costs associated with these extended warranty contracts are recognized when incurred.

Shipping and Handling Costs

Shipping and handling charges to customers are included in net revenues, and the associated costs incurred are recorded in cost of revenues.

Legal Proceedings and Litigations

We are involved in legal proceedings on an ongoing basis. If we believe that a loss arising from such matters is probable and can be reasonably estimated, we accrue the estimated liability in our financial statements. If only a range of estimated losses can be determined, we accrue an amount within the range that, in our judgment, reflect the most likely outcome; if none of the estimates within that range is a better estimate than any other amount, we accrue the low end of the range.

Research and development

Research and development expense is expensed as incurred and includes the costs associated with the research and development of new products and enhancements to existing products. These costs primarily include compensation costs, including stock-based compensation expense, outside consulting expenses, costs associated with conducting clinical and pre-commercialization trial and testing, allocations of corporate overhead expenses including facilities and IT costs, equipment costs and depreciation and amortization.

Advertising costs

The cost of advertising and media is expensed as incurred. For the year ended December 31, 2015, 2014 and 2013 advertising costs totaled $23.4 million, $26.9 million and $26.0 million, respectively.

Common stock repurchase

We repurchase our own common stock from time to time in the open market when our Board of Directors approve a stock repurchase program. We account for these repurchases under the accounting guidance for equity where we allocate the total repurchase value that are in excess over par between additional paid in capital and retained earnings. All shares repurchased are retired.

Operating leases

We currently lease office spaces, automobiles and equipment under operating leases with original lease periods of up to 9 years. Certain of these leases have free or escalating rent payment provisions and lease incentives provided by the landlord. We recognize rent expense under such leases on a straight-line basis over the term of the lease as certain leases have adjustments for market provisions.

Income taxes

We make certain estimates and judgments in determining income tax expense for financial statement purposes. These estimates and judgments occur in the calculation of certain tax assets and liabilities, which arise from differences in the timing of recognition of revenue and expense for tax and financial statement purposes.

As part of the process of preparing our consolidated financial statements, we are required to estimate our income taxes in each of the jurisdictions in which we operate. This process involves us estimating our current tax exposure under the applicable tax laws and assessing temporary differences resulting from differing treatment of items for tax and accounting purposes. These differences result in deferred tax assets and liabilities, which are included in our Consolidated Balance Sheets.

We account for uncertainty in income taxes pursuant to authoritative guidance based on a two-step approach to recognize and measure uncertain tax positions taken or expected to be taken in a tax return. The first step is to determine if the weight of available evidence indicates that it is more likely than not that the tax position will be sustained on audit based on its technical merits, including resolution of any related appeals or litigation processes. The second step is to measure the tax benefit as the largest amount that is more than 50% likely to be realized upon ultimate settlement. We adjust reserves for our uncertain tax positions due to changing facts and circumstances, such as the closing of a tax audit, or refinement of estimates due to new information. To the extent that the final outcome of these matters is different than the amounts recorded, such differences will impact our tax provision in our Consolidated Statements of Operations in the period in which such determination is made.

We assess the likelihood that we will be able to realize our deferred tax assets. Should there be a change in our ability to realize our deferred tax assets, our tax provision would increase in the period in which we determine that it is more likely than not that we cannot realize our deferred tax assets. We consider all available evidence, both positive and negative, including historical levels of income, expectations and risks associated with estimates of future taxable income and ongoing prudent and feasible tax planning strategies in assessing the need for a valuation allowance. If it is more likely than not that we will not realize our deferred tax assets, we will increase our provision for taxes by recording a valuation allowance against the deferred tax assets that we estimate will not ultimately be realizable. The available positive evidence at December 31, 2015 included historical operating profits and a projection of future income sufficient to realize most of our remaining deferred tax assets. As of December 31, 2015, it was considered more likely than not that our deferred tax assets would be realized with the exception of certain foreign loss carryovers as we are unable to forecast sufficient future profits to realize the deferred tax assets.

As of December 31, 2015, U.S. income taxes and foreign withholding taxes associated with the repatriation of undistributed earnings of foreign subsidiaries were not provided for on a cumulative total of $359.8 million. We intend to reinvest these earnings indefinitely in our foreign subsidiaries. If these earnings were distributed in the form of dividends or otherwise, or if the shares of the relevant foreign subsidiaries were sold or otherwise transferred, we would be subject to additional U.S. income taxes subject to an adjustment for foreign tax credit, and foreign withholding taxes. Determination of the amount of unrecognized deferred income tax liability related to these earnings is not practicable.

Accounting guidance for stock-based compensation prohibits recognition of a deferred income tax asset for excess tax benefits due to stock option exercises that have not yet been realized through a reduction in income taxes payable. We follow the tax law ordering method to determine when excess tax benefits have been realized and consider only the direct impacts of awards when calculating the amount of windfalls or shortfalls.

Stock-based compensation

We recognize stock-based compensation cost for only those shares ultimately expected to vest on a straight-line basis over the requisite service period of the award. We use the Black-Scholes option pricing model to determine the fair value of employee stock purchase plan shares. We estimate the fair value of market-performance based restricted stock units using a Monte Carlo simulation model which requires the input of assumptions, including expected term, stock price volatility and the risk-free rate of return. In addition, judgment is also required in estimating the number of stock-based awards that are expected to be forfeited. Forfeitures are estimated based on historical experience at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. The assumptions used in calculating the fair value of share-based payment awards represent management’s best estimates, but these estimates involve inherent uncertainties and the application of management’s judgment. As a result, if factors change and we use different assumptions, our stock-based compensation expense could be materially different in the future.

Medical Device Excise Taxes

In accordance with the Patient Protection and Affordable Care Act, effective January 1, 2013, we began to incur an excise tax on sales of medical devices in the U.S. In March 2014, we were informed by IRS that our aligners are not subject to the medical device excise tax ("MDET") which we had been paying and expensing in selling, general and administrative expenses in the Consolidated Statements of Operations since January 1, 2013; however, our scanners are still subject to the MDET. Beginning in March 2014, we ceased expensing and paying the MDET for aligners. In the first quarter of 2015, the IRS approved our MDET refund claim of $6.8 million refund of MDET paid in 2013 related to our aligners; reducing expense for the year ended December 31, 2015.

Comprehensive income

Comprehensive income includes all changes in equity during a period from non-owner sources. Comprehensive income, including unrealized gains and losses on available-for-sale securities and foreign currency translation adjustments, are reported net of their related tax effect.

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (" FASB") released Accounting Standards Update ("ASU") 2014-9 "Revenue from Contracts with Customers" to supersede nearly all existing revenue recognition guidance under GAAP. The core principle of the standard is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for the goods or services. The new standard defines a five step process to achieve this core principle and, in doing so, it is possible more judgment and estimates may be required within the revenue recognition process than required under existing GAAP including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. In addition, the new standard requires that reporting companies disclose the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers.

In August 2015, the FASB deferred the effective date of the update by one year, with early adoption on the original effective date permitted. We are required to adopt this standard starting in the first quarter of fiscal year 2018 using either of two methods: (i) retrospective to each prior reporting period presented with the option to elect certain practical expedients as defined within the standard; or (ii) retrospective with the cumulative effect of initially applying the standard recognized at the date of initial application and providing certain additional disclosures as defined per the standard. We have not yet selected a transition method, and are in the process of determining the impact that the new standard will have on our consolidated financial statements.

In April 2015, the FASB issued ASU No. 2015-05, "Customer's Accounting for Fees Paid in a Cloud Computing Arrangement." providing guidance to entities about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, the entity should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the entity should account for the arrangement as a service contract. The new guidance does not change the accounting for an entity's accounting for service contracts. The updated standard becomes effective for interim and annual reporting periods beginning after December 15, 2015. We adopted this ASU in January, 2016, and we do not expect it to have a material impact on our consolidated financial statements and related disclosures.

In November 2015, the FASB issued ASU 2015-17, "Income Taxes" (Topic 740), to simplify the presentation of deferred income taxes. Under the new standard, both deferred tax liabilities and assets are required to be classified as noncurrent in a classified balance sheet. ASU 2015-17 will become effective for fiscal years, and the interim periods within those years, beginning after December 15, 2016, with early adoption permitted. The new guidance has been adopted on a prospective basis by the Company for the year ended December 31, 2015, thus resulting in the reclassification of $30.1 million of current deferred tax assets to noncurrent on the accompanying Consolidated Balance Sheets. The prior reporting period was not retrospectively adjusted. The adoption of this guidance had no impact on our Consolidated Statements of Operations or Consolidated Statements of Comprehensive Income.

In February 2016, the FASB issued ASU No. 2016-02, “Leases” (topic 842). The FASB issued this update to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The updated guidance is effective for annual periods beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption of the update is permitted. The Company is evaluating the impact of the adoption of this update on our consolidated financial statements and related disclosures.