What are your options if you learn of a mistake on your income tax return?

If you filed an income tax return and believed it to be true and correct when originally filed, you have no obligation to file an amended income tax return. There is no statute or caselaw that requires you to notify the IRS of your error. Indeed, the concept of an amended income tax return is not recognized in the Tax Code—taxpayers have no obligation to file them, and the IRS has no obligation to accept them. The Supreme Court, in Badaracco v. Commissioner, 464 U.S. 386 (1984), noted that amended returns are "a creature of administrative origin and grace." Indeed, even if you did not believe your return to be true and correct when you originally filed it, you still have no duty to file an amended income tax return, and filing one will not help you undo criminal exposure from your previously filed return. See Badaracco, 464 U.S. at 397.

Treasury Regulation 1.451-1(a), at first blush, appears to provide an obligation to file an amended return:

If a taxpayer ascertains that an item should have been included in gross income in a prior taxable year, he should, if within the period of limitation, file an amended return and pay any additional tax due.

Amended returns are also mentioned in Treasury Regulation §§ 301.6211–1(a), 301.6402–3(a), 1.461–1(a)(3)(i). Section 6213(g)(1) of the Tax Code itself also mentions an amended return. The Supreme Court, however, noted in Badaracco that “none of these provisions, however, requires the filing of such a return.” Accordingly, you have no obligation to file an amended return despite any error that you may find in your original income tax return.

https://www.keimtaxlaw.com/do-you-have-a-legal-obligation-to-file-an-amended-income-tax-return