26 CFR § 1.162-25 - Deductions with respect to noncash fringe benefits.
(b) Employee. If an employer provides the use of a vehicle (as defined in § 1.61-21(e)(2)) to an employee as a noncash fringe benefit and includes the entire value of the benefit in the employee's gross income without taking into account any exclusion for a working condition fringe allowable under section 132 and the regulations thereunder, the employee may deduct that value multiplied by the percentage of the total use of the vehicle that is in connection with the employer's trade or business (business value). For taxable years beginning before January 1, 1990, the employee may deduct the business value from gross income in determining adjusted gross income. For taxable years beginning on or after January 1, 1990, the employee may deduct the business value only as a miscellaneous itemized deduction in determining taxable income, subject to the 2-percent floor provided in section 67. If the employer determines the value of the noncash fringe benefit under a special accounting rule that allows the employer to treat the value of benefits provided during the last two months of the calendar year or any shorter period as paid during the subsequent calendar year, then the employee must determine the deduction allowable under this paragraph (b) without regard to any use of the benefit during those last two months or any shorter period. The employee may not use a cents-per-mile valuation method to determine the deduction allowable under this paragraph (b).