Revenue Procedures are official written statements of the IRS. According to the Internal Revenue Manual, "a revenue procedure (Rev. Proc.) is issued to assist taxpayers in complying with procedural issues that deal with tax return preparation and compliance". (IRM 4.10.7.2.6).
Numbering:
Revenue Procedures are numbered consecutively each year ( i.e. Rev. Proc. 2014-6 is the 6th revenue procedure issued in 2014). It should be noted that many revenue procedures are issued regularly each year. For example, the first procedure issued each year (2012-1, 2013-1, 2014-1, etc.) provides the current procedures for obtaining letter rulings, determination letters and closing agreements.
Authoritative Value:
"Rulings do not have the force and effect of Treasury Department Regulations, but they may be used as precedents. In applying published rulings, the effects of subsequent legislation, regulations, court decisions, rulings, and procedures must be considered. Caution is urged against reaching the same conclusion in other cases, unless the facts and circumstances are substantially the same" (IRM 4.10.7.2.6.1, Authority of Rulings and Procedure).
Revenue Procedures may be used as "substantial authority" to avoid the substantial understatement penalty. (Rev. Proc. 2010-15).
Internal Revenue Bulletin by Revenue Procedures are available on Westlaw and Lexis Advance from 1955 - present.