Step 1 of 8 · The return being corrected

File Form 943-X — Adjusted Employer's Annual Federal Tax Return for Agricultural Employees or Claim for Refund

Correct a Form 943 you already filed. Each line takes the corrected total (column 1), what you originally reported (column 2), and the difference (column 3); the tax lines also take the tax that difference produces (column 4).

Filing a year for the first time? That is Form 943.