"The purpose of ยง 481 is to prevent either a distortion of taxable income or a windfall to the taxpayer arising from a change in accounting method when the statute of limitations bars reopening of the taxpayer's earlier returns." Pinkston v. Commissioner, T.C. Memo. 2020-44, 2020 WL 1847110, at *3 (quoting Suzy's Zoo v. Commissioner, 273 F.3d 875, 883 (9th Cir. 2001), aff'g 114 T.C. 1 (2000)). All section references are to the Internal Revenue Code in effect for the years in issue, and all Rule references are to the Tax Court Rules of Practice and Procedure, unless we say otherwise.