The Form 1040X, Amended U.S. Singular Income Tax Return, isn't acknowledged electronically; But, only tax return might be electronically filed. You should file or document Form 1040X on paper and send the mail to the IRS.The Form 1040X, Amended U.S. Singular Income Tax Return, isn't acknowledged electronically; But, only tax return might be electronically filed. You should file or document Form 1040X on paper and send the mail to the IRS.The Form 1040X, Amended U.S. Singular Income Tax Return, isn't acknowledged electronically; But, only tax return might be electronically filed. You should file or document Form 1040X on paper and send the mail to the IRS.