Private letter rulings (PLRs), in the United States, are written decisions by the Internal Revenue Service (IRS) in response to taxpayer requests for guidance.
[1] A letter ruling is "a written statement issued to a taxpayer by an Associate Chief Counsel Office of the Office of Chief Counsel or by the Tax Exempt and Government Entities Division that interprets and applies the tax laws to a specific set of facts.
PLRs from 1997 onwards are available to the public through the IRS Electronic reading room (see 26 U.S.C. § 6110).
A technical advice memorandum (TAM) is similar to a letter ruling, but is typically obtained during the course of an IRS examination.
[3] The request for advice must concern the interpretation and application of the internal revenue laws, tax treaties, regulations, revenue rulings, or other precedents to a specific set of facts to determine the correct tax treatment for an item in a year under audit or on appeal.