How do I use Form 1040-X to amend my return?

Form 1040-X has three columns: Column A (amounts as originally reported), Column B (the net change), and Column C (corrected amounts). Fill in only the lines that changed and explain the reason for each change in Part III. Attach any supporting documents like corrected W-2s or 1099s. You must file a separate 1040-X for each tax year you are amending — one form cannot cover multiple years.