Use this form to correct errors on a Form CT-1 that you previously filed: Tier I Employee tax, Tier I Employee Medicare tax, and Tier II Employee tax; Tier I Employer tax, Tier I Employer Medicare tax, and Tier II Employer tax; Exemption for qualified employer's share of Tier I tax on compensation paid to qualified employees; and Credit for qualified employer's share of Tier I tax on compensation paid to qualified employees. Current Revision Form CT-1 X PDF Instructions for Form CT-1 X (Print Version PDF) Recent Developments None at this time. Other Items You May Find Useful All Form CT-1 X Revisions Notice 2015-2, Application of Retroactive Increase in Excludable Transit Benefits Notice 2016-6, Application of Retroactive Increase in Excludable Transit Benefits About Publication 15, (Circular E), Employer's Tax Guide About Publication 556, Examination of Returns, Appeal Rights, and Claims for Refund Publication 966, Electronic Federal Tax Payment System, A Guide To Getting Started PDF Revenue Procedure 2017-28 Other Current Products Related About Form 843, Claim for Refund and Request for Abatement About Form 945-A, Annual Record of Federal Tax Liability About Form CT-1, Employer's Annual Railroad Retirement Tax Return About Form W-2, Wage and Tax Statement About Form W-2 C, Corrected Wage and Tax Statements About Form W-3, Transmittal of Wage and Tax Statements About Form W-3 C, Transmittal of Corrected Wage and Tax Statements About Form W-12, IRS Paid Preparer Tax Identification Number (PTIN) Application and Renewal