ACCOUNTING PRONOUNCEMENTS RECENTLY ADOPTED	9 Months Ended
Sep. 30, 2021
Accounting Policies [Abstract]
ACCOUNTING PRONOUNCEMENTS RECENTLY ADOPTED	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES For each accounting topic that is addressed in a separate footnote, the description of the accounting policy can be found in the related footnote. Other significant policies are described below. Use of Estimates Accounting estimates are an integral part of the consolidated financial statements. These estimates require the use of judgments and assumptions that may affect the reported amounts of assets, liabilities, and expenses in the period presented. The Company believes that the accounting estimates and related assumptions employed by the Company are appropriate and the resulting balances are reasonable under the circumstances. However, due to the inherent uncertainties involved in making estimates, the actual results could differ from the original estimates, requiring adjustments to these balances in future periods. Cash and Cash Equivalents Cash and cash equivalents include cash on hand, cash in banks, and money market funds with maturities of three months or less. All short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates are classified as cash equivalents. Restricted Cash Cash and cash equivalents that are restricted as to withdrawal or use under the terms of certain contractual agreements are recorded in “Other current assets” and “Other assets” on the Company’s Condensed Consolidated Balance Sheets. As of December 31, 2020 and September 30, 2021, restricted cash within “Other current assets” and “Other assets” totaled $32 million and $49 million, respectively. Inventory and Inventory Valuation Inventory is stated at the lower of cost or net realizable value (“LCNRV”) and consists of raw materials, work-in-progress, and finished goods. The Company primarily computes cost using standard cost, which approximates cost on the first-in, first-out (“FIFO”) basis. Net realizable value (“NRV”) is the estimated selling price of inventory in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The Company assesses the valuation of inventory and periodically adjusts its value for estimated excess and obsolete inventory based upon expectations of future demand and market conditions, as well as damaged or otherwise impaired goods. During the three and nine months ended September 30, 2021, the Company recorded a $31 million charge to write-down inventory to its net realizable value, with the charge reflected in Cost of revenues in the Condensed Consolidated Statement of Operations. Substantially all of the Company’s inventory balance as of September 30, 2021 is classified as raw materials, which includes customized purchased components. Cost of Vehicle Revenue Cost of vehicle revenue includes direct parts, material and labor costs, manufacturing overhead (e.g., depreciation of machinery and tooling), inbound shipping and logistics costs, and reserves for estimated warranty costs. Cost of vehicle revenue also includes adjustments to write down the carrying value of inventory when it exceeds its estimated NRV and to provide for on-hand inventory that is either obsolete or in excess of forecasted demand. Fair Value Measurements A three-level valuation hierarchy, based upon observable and unobservable inputs, is used for fair value measurements. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect market assumptions based on the best evidence available. These two types of inputs create the following fair value hierarchy: •Level 1 – Quoted prices for identical instruments in active markets •Level 2 – Quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-derived valuations whose significant inputs are observable •Level 3 – Instruments with model-derived valuations whose significant inputs are unobservable The Company’s money market funds were classified within Level 1 of the fair value hierarchy because they were valued using quoted prices in active markets. As of December 31, 2020 and September 30, 2021, money market funds totaled $2,782 million and $4,983 million, respectively. During the nine months ended September 30, 2021, there were no transfers between the levels of the fair value hierarchy. On July 23, 2021 the Company issued $2.5 billion aggregate principal amount of unsecured senior convertible promissory notes due July 23, 2026 in a private offering (“2021 Convertible Notes”) and has made an irrevocable election to account for the 2021 Convertible Notes under the Fair Value Option in accordance with the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification Topic 825, Financial Instruments. As of September 30, 2021, the fair value of the 2021 Convertible Notes recorded on the Condensed Consolidated Balance Sheet totaled $2,958 million. Refer to Note 6 "Debt" for further information on the fair value of the 2021 Convertible Notes. Research and Development Costs Research and development (“R&D”) costs consist primarily of personnel costs for teams in engineering and research, prototyping expenses, contract and professional services, amortized equipment costs, and allocation of indirect costs. R&D costs are expensed as incurred. Marketing, Advertising, and Promotion Marketing, advertising, and promotion costs are included as part of Selling, general, and administrative expense in the Conde nsed C onsolidated S tatement of O perations, and such costs are expensed as they are incurred. During the three months ended September 30, 2020 and 2021, the Company recognized marketing and promotion costs of $1 million and $7 million, respectively. During the nine months ended September 30, 2020 and 2021, the Company recognized marketing and promotion costs of $3 million and $11 million, respectively. Advertising costs recognized during the three and nine months ended September 30, 2020 and 2021 were immaterial. Concentration of Risk Counterparty Credit Risk Financial instruments that potentially subject the Company to concentration of counterparty credit risk consist of cash and cash equivalents, deposits, and loans. As of December 31, 2020 and September 30, 2021, all of the Company’s cash and cash equivalents were placed at financial institutions that management believes are of high credit quality. These amounts are typically in excess of insured limits. Supply Risk The Company is subject to risks related to its dependence on its suppliers, the majority of which are single source providers of parts or components for the Company’s products. Any inability of the Company’s suppliers to deliver necessary product components, including semiconductors, at timing, prices, quality, and volumes that are acceptable to the Company could have a material and adverse impact on Rivian’s business, growth prospects, and financial and operating results. The Company’s manufacturing facility in Normal, Illinois (the “Normal Factory”) is operational, and Rivian is continuing to invest in the Normal Factory. The Company’s ability to continue to prepare for and sustain production depends, among other things, on the readiness and solvency of suppliers and vendors through all macroeconomic factors, including factors resulting from the COVID-19 pandemic.ACCOUNTING PRONOUNCEMENTS RECENTLY ADOPTEDIn August 2020, the FASB issued Accounting Standards Update (“ASU”) 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity. The ASU simplifies (i) the accounting for convertible financing instruments issued, including preferred stock, (ii) the derivatives scope exception for contracts in an entity’s own equity, and (iii) the calculation of earnings per share. Early adoption by private companies is permissible, and the Company elected to early adopt the new accounting standard on January 1, 2021. The adoption of this standard did not have a material impact on the Company’s consolidated financial statements and disclosures.

For each accounting topic that is addressed in a separate footnote, the description of the accounting policy can be found in the related footnote. Other significant policies are described below.

Accounting estimates are an integral part of the consolidated financial statements. These estimates require the use of judgments and assumptions that may affect the reported amounts of assets, liabilities, and expenses in the period presented. The Company believes that the accounting estimates and related assumptions employed by the Company are appropriate and the resulting balances are reasonable under the circumstances. However, due to the inherent uncertainties involved in

Cash and cash equivalents include cash on hand, cash in banks, and money market funds with maturities of three months or less. All short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates are classified as cash equivalents.

Cash and cash equivalents that are restricted as to withdrawal or use under the terms of certain contractual agreements are recorded in “Other current assets” and “Other assets” on the Company’s Condensed Consolidated Balance Sheets. As of December 31, 2020 and September 30, 2021, restricted cash within “Other current assets” and “Other assets” totaled $32 million and $49 million, respectively.

Inventory is stated at the lower of cost or net realizable value (“LCNRV”) and consists of raw materials, work-in-progress, and finished goods. The Company primarily computes cost using standard cost, which approximates cost on the first-in, first-out (“FIFO”) basis. Net realizable value (“NRV”) is the estimated selling price of inventory in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The Company assesses the valuation of inventory and periodically adjusts its value for estimated excess and obsolete inventory based upon expectations of future demand and market conditions, as well as damaged or otherwise impaired goods.

During the three and nine months ended September 30, 2021, the Company recorded a $31 million charge to write-down inventory to its net realizable value, with the charge reflected in Cost of revenues in the Condensed Consolidated Statement of Operations.

Substantially all of the Company’s inventory balance as of September 30, 2021 is classified as raw materials, which includes customized purchased components.

Cost of vehicle revenue includes direct parts, material and labor costs, manufacturing overhead (e.g., depreciation of machinery and tooling), inbound shipping and logistics costs, and reserves for estimated warranty costs. Cost of vehicle revenue also includes adjustments to write down the carrying value of inventory when it exceeds its estimated NRV and to provide for on-hand inventory that is either obsolete or in excess of forecasted demand.

A three-level valuation hierarchy, based upon observable and unobservable inputs, is used for fair value measurements. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect market assumptions based on the best evidence available. These two types of inputs create the following fair value hierarchy:

•Level 2 – Quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-derived valuations whose significant inputs are observable

The Company’s money market funds were classified within Level 1 of the fair value hierarchy because they were valued using quoted prices in active markets. As of December 31, 2020 and September 30, 2021, money market funds totaled $2,782 million and $4,983 million, respectively. During the nine months ended September 30, 2021, there were no transfers between the levels of the fair value hierarchy.

On July 23, 2021 the Company issued $2.5 billion aggregate principal amount of unsecured senior convertible promissory notes due July 23, 2026 in a private offering (“2021 Convertible Notes”) and has made an irrevocable election to account for the 2021 Convertible Notes under the Fair Value Option in accordance with the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification Topic 825, Financial Instruments. As of September 30, 2021, the fair value of the 2021 Convertible Notes recorded on the Condensed Consolidated Balance Sheet totaled $2,958 million. Refer to Note 6 "Debt" for further information on the fair value of the 2021 Convertible Notes.

Research and development (“R&D”) costs consist primarily of personnel costs for teams in engineering and research, prototyping expenses, contract and professional services, amortized equipment costs, and allocation of indirect costs. R&D costs are expensed as incurred.

Marketing, advertising, and promotion costs are included as part of Selling, general, and administrative expense in the Conde nsed C onsolidated S tatement of O perations, and such costs are expensed as they are incurred. During the three months ended September 30, 2020 and 2021, the Company recognized marketing and promotion costs of $1 million and $7 million, respectively. During the nine months ended September 30, 2020 and 2021, the Company recognized marketing and promotion costs of $3 million and $11 million, respectively. Advertising costs recognized during the three and nine months ended September 30, 2020 and 2021 were immaterial.

Financial instruments that potentially subject the Company to concentration of counterparty credit risk consist of cash and cash equivalents, deposits, and loans. As of December 31, 2020 and September 30, 2021, all of the Company’s cash and cash equivalents were placed at financial institutions that management believes are of high credit quality. These amounts are typically in excess of insured limits.

The Company is subject to risks related to its dependence on its suppliers, the majority of which are single source providers of parts or components for the Company’s products. Any inability of the Company’s suppliers to deliver necessary product components, including semiconductors, at timing, prices, quality, and volumes that are acceptable to the Company could have a material and adverse impact on Rivian’s business, growth prospects, and financial and operating results.