26 C.F.R. § 1.274-1
Section 274 disallows in whole, or in part, certain expenditures for entertainment, gifts and travel which would otherwise be allowable under Chapter 1 of the Code. The requirements imposed by section 274 are in addition to the requirements for deductibility imposed by other provisions of the Code. If a deduction is claimed for an expenditure for entertainment, gifts, or travel, the taxpayer must first establish that it is otherwise allowable as a deduction under Chapter 1 of the Code before the provisions of section 274 become applicable. An expenditure for entertainment, to the extent it is lavish or extravagant, shall not be allowable as a deduction. The taxpayer should then substantiate such an expenditure in accordance with the rules under section 274(d). See § 1.274-5 . Section 274 is a disallowance provision exclusively, and does not make deductible any expense which is disallowed under any other provision of the Code. Similarly, section 274 does not affect the includability of an item in, or the excludability of an item from, the gross income of any taxpayer. For specific provisions with respect to the deductibility of expenditures: for an activity of a type generally considered to constitute entertainment, amusement, or recreation, and for a facility used in connection with such an activity, as well as certain travel expenses of a spouse, etc., see § 1.274-2 ; for expenses for gifts, see § 1.274-3 ; for expenses for foreign travel, see § 1.274-4 ; for expenditures deductible without regard to business activity, see § 1.274-6 ; and for treatment of personal portion of entertainment facility, see § 1.274-7 .
26 C.F.R. §1.274-1