Corporations use Form 1120-X to: Correct a Form 1120 (or Form 1120-A, if applicable) as originally filed, or as later adjusted by an amended return, a claim for refund, or an examination. Make certain elections after the prescribed deadline. Current Revision Form 1120-X PDF Recent Developments None at this time. Other Items You May Find Useful All Revisions for Form 1120-X About Form 1139, Corporation Application for Tentative Refund About Form 3115, Application for Change in Accounting Method About Form 4466, Corporation Application for Quick Refund of Overpayment of Estimated Tax About Publication 542, Corporations Other Current Products Related About Form 1120, U.S. Corporation Income Tax Return About Form 3800, General Business Credit About Form 8302, Direct Deposit of Tax Refund of $1 Million or More About Form 8886, Reportable Transaction Disclosure Statement