Official Resources
Primary sources for cost basis rules.
Educational information only, not tax, legal, or investment advice. Rules change; check the official sources listed on this page or talk with a qualified professional about your situation. Full disclaimer.
Official sources behind every guide on this site.
- IRS Publication 550: Investment Income and Expenses (basis of investment property, wash sales, nondividend distributions)
- IRS Publication 551: Basis of Assets
- IRS: Instructions for Form 1099-B (covered securities, boxes 1e, 1g, 5 and 12)
- IRS: Instructions for Form 8949 (reporting sales, basis adjustments and codes)
- IRS: Instructions for Form 1099-DIV (box 3 nondividend distributions)
- IRS Topic No. 703: Basis of assets
- IRS Topic No. 409: Capital gains and losses
- Treas. Reg. § 1.6045-1: Returns of information of brokers (covered security definitions and dates)
- Treas. Reg. § 1.1012-1: Basis of property (FIFO default, adequate identification, average basis)
- 26 U.S.C. § 1012: Basis of property, cost
- 26 U.S.C. § 1014: Basis of property acquired from a decedent
- 26 U.S.C. § 1015: Basis of property acquired by gifts
- 26 U.S.C. § 1016: Adjustments to basis
- 26 U.S.C. § 1091: Loss from wash sales of stock or securities
- 26 U.S.C. § 301(c): Distributions in excess of earnings and profits
- IRS Revenue Ruling 2008-5 (wash sale when replacement shares are bought in an IRA), Internal Revenue Bulletin 2008-3 (PDF)
- IRS: About Form 8971 (basis consistency for inherited property)
- IRS: About Form 8937, Report of organizational actions affecting basis of securities
- IRS Publication 559: Survivors, Executors, and Administrators
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Last reviewed: November 2026