A Revenue Procedure (Rev. Proc.) is an official statement of a procedure that affects the rights or duties of taxpayers or other members of the public under the Internal Revenue Code, related statutes, tax treaties and regulations and that should be a matter of public knowledge. It is also published in the Internal Revenue Bulletin. While a revenue ruling generally states an IRS position, a revenue procedure provides return filing or other instructions concerning an IRS position. For example, a revenue procedure might specify how those entitled to deduct certain automobile expenses should compute them by applying a certain mileage rate in lieu of calculating actual operating expenses. (IRS Website - Understanding IRS Guidance - A Brief Primer )