"Generally, regulations are first published in proposed form in a Notice of Proposed Rulemaking (NPRM)." (IRS website) Proposed regulations are published in the Federal Register and in the Internal Revenue Bulletin.
"Proposed regulations provide guidance concerning Treasury’s interpretation of a Code section. The public is given an opportunity to comment on a proposed regulation and a public hearing may be held if a sufficient number of requests to speak at a hearing are received. . ." (Classes of Regulations, IRM § 188.8.131.52.3.3)
As per the Bluebook citation quoted below, citations to IRS tax regulations often do not include a reference to the pertinent CFR title (title 26). The CFR title number is replaced with "Treas. Reg." or "Prop. Treas. Reg."
The following citation resources may be informative.
Below are pertinent abbreviations.
Warning: Researchers should independently verify the currency of any proposed rule.
Below are links either to sources offering proposed regulatory material--specifically sources offering the Federal Register, where proposed regulations are published. These sources are not focused on tax regulatory material. Warning: Researchers should independently verify the currency of any proposed rule.