SECTION 1. PURPOSE

This revenue procedure updates Rev. Proc. 97–58, 1997–2 C.B. 587, by providing optional standard mileage rates for employees, self-employed individuals, or other taxpayers to use in computing the deductible costs paid or incurred on or after January 1, 1999, of operating an automobile for business, charitable, medical, or moving expense purposes. This revenue procedure also provides rules under which the amount of ordinary and necessary expenses of local travel or transportation away from home that are paid or incurred by an employee will be deemed substantiated under § 1.274–5T of the temporary Income Tax Regulations when a payor (the employer, its agent, or a third party) provides a mileage allowance under a reimbursement or other expense allowance arrangement to pay for such expenses. Use of a method of substantiation described in this revenue procedure is not mandatory and a taxpayer may use actual allowable expenses if the taxpayer maintains adequate records or other sufficient evidence for proper substantiation.