What the IRS says: “The IRS believes there's income missing from your return and is asking you to check and file Form 1040-X if needed.” Here’s what it actually means, your deadline, and exactly how to respond.
Unlike a CP2000, the CP2057 proposes nothing — it tells you the IRS saw a mismatch and expects you to fix it yourself. No response form, no proposed balance. If the IRS is right, amend; if not, keep your documentation ready, because a CP2000 may follow.
Notice family: Underreporter & Audit — The IRS thinks your return doesn't match its records — or wants to examine it. These notices carry hard response deadlines, and a written response with documentation is exactly how they get resolved.
Reconcile the flagged income against your records
If missing income is real: file Form 1040-X and pay the difference
If your return is correct: no filing needed — but document why and keep it
Watch for a follow-up CP2000 and respond to that formally if it arrives
No letter is required by the IRS here — but if the flagged income is not yours or already reported, sending a short explanation letter anyway creates a paper trail that often prevents the CP2000 stage entirely.
Describe the notice and your side of it — use placeholders, never your SSN or account numbers (the letter keeps [YOUR NAME]-style fields so you fill in the real details privately before mailing). A mail-ready draft with an enclosure checklist comes back in ~20 seconds.
Your IRS response letter draft will appear here.
The IRS believes there's income missing from your return and is asking you to check and file Form 1040-X if needed. In practice: Unlike a CP2000, the CP2057 proposes nothing — it tells you the IRS saw a mismatch and expects you to fix it yourself. No response form, no proposed balance. If the IRS is right, amend; if not, keep your documentation ready, because a CP2000 may follow.
There is no fixed response deadline on this notice, but acting promptly keeps your options open. The respond-by date printed on your own notice always controls.
No letter is required by the IRS here — but if the flagged income is not yours or already reported, sending a short explanation letter anyway creates a paper trail that often prevents the CP2000 stage entirely.