Use this form to correct errors on a Form CT-1 that you previously filed. 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 Make a payment Other current products Related items About Form 945-A, Annual Record of Federal Tax Liability About Form CT-1, Employer's Annual Railroad Retirement Tax Return