Rev. Proc. 2021-52, page 883.

This revenue procedure will update Rev. Proc. 2020-54, 2020-53 I.R.B. 1806, and identifies circumstances under which the disclosure on a taxpayer’s income tax return with respect to an item or position is adequate for the purpose of reducing the understatement of income tax under section 6662(d) of the Internal Revenue Code (relating to the substantial understatement aspect of the accuracy-related penalty), and for the purpose of avoiding the tax return preparer penalty under section 6694(a) (relating to understatements due to unreasonable positions) with respect to income tax returns. This revenue procedure will apply to any income tax return filed on 2021 tax forms for a taxable year beginning in 2021 and to any income tax return filed in 2022 on 2021 tax forms for short taxable years beginning in 2022.