COHAN RULE

Cohan rule (koh-han).Tax. A former rule that a taxpayer may approximate travel and entertainment expenses when no records exist if the taxpayer has taken all possible steps to provide documentation. • Since 1962, travel and entertainment expenses have been only partly deductible and must be carefully documented, but courts may apply the Cohan reasoning to other items.Cohan v. Commissioner, 39 F.2d 540 (2d Cir. 1930). [Cases: Internal Revenue  3377, 4536. C.J.S. Internal Revenue §§ 647, 671, 673, 799.] [Blacks Law 8th]