How many years back can the IRS or California FTB audit me?

Three years federally, four for California — with expansions that matter. The IRS generally must assess additional tax within three years of the return's filing (26 U.S.C. § 6501); the period doubles to six years when gross income is understated by more than 25%, and never closes for fraud or a never-filed return. The Franchise Tax Board gets four years (Revenue and Taxation Code section 19057) and likewise faces no limit for fraud or non-filing — and because the FTB piggybacks on federal results, a federal adjustment reopens California exposure: taxpayers must report federal changes within six months, or the FTB may assess at any time (section 18622). Collection differs sharply: the IRS generally has ten years from assessment to collect (26 U.S.C. § 6502), while California's collection statute runs twenty (section 19255). Audit selection is not accusation — but responses are deadline-driven, and appeal rights (90 days to Tax Court; 60 days to protest an FTB notice) expire quickly.

Authority: 26 U.S.C. § 6501; Cal. Rev. & Tax. Code § 19057