When to amend
Correct material errors, missed elections, or late K‑1 items. Consider whether an accounting method change is more appropriate.
Forms & filing
Use the appropriate amended return form (e.g., 1120X for C‑Corps, amended 1065 for partnerships) with explanations and schedules.
State considerations
Many states require separate amended filings and adjustments to prior‑year carryforwards.
Owners & basis
Amended entity returns may require owners to file amended personal returns; track basis and capital accounts carefully.