Yes. The IRS now accepts electronically filed amended 1120-S returns for tax years 2019 and forward through the Modernized e-File (MeF) system. To amend, check the “Amended Return” box on the face of the return, attach a written statement detailing each change and the reason for it, and issue corrected Schedule K-1s to all affected shareholders. In addition to the entity-level amendment, each shareholder whose individual return is affected must file Form 1040-X separately. Coordinate timing so shareholders receive corrected K-1s before amending their personal returns.