What the IRS says: “The IRS found a miscalculation on your return, corrected it, and you now owe money.” Here’s what it actually means, your deadline, and exactly how to respond.
A 'math error' notice — but the term covers far more than arithmetic: mismatched SSNs on dependents, credit computations, and IRS data-entry of paper returns all fire CP11s. Math-error assessments skip the usual deficiency procedures, which makes the 60-day window critical: dispute within it and the IRS must abate and use normal procedures; miss it and you're stuck with the harder audit-reconsideration route.
Notice family: Return Adjustments — The IRS changed something on your return — math corrections, credit adjustments, payment mismatches. Often correct, frequently not. You typically have 60 days to dispute a change you disagree with.
60 days — to request abatement of the math-error assessment with full rights.
Counted in calendar days from the notice date. The exact respond-by date printed on your notice always controls — check page 1.
Compare the notice's 'your figures vs ours' section against your return copy
If the IRS is right: pay or set up a plan by the due date
If wrong: dispute IN WRITING within 60 days — this forces abatement and full appeal rights
Phone disputes work but always back them with the letter; the 60-day right is preserved in writing
A 60-day math-error dispute letter is short and powerful: identify the change, state you request abatement under IRC 6213(b), attach the proof (SSN card copy, corrected computation). The IRS must then reverse and, if it still disagrees, issue a proper deficiency notice you can contest.
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 found a miscalculation on your return, corrected it, and you now owe money. In practice: A 'math error' notice — but the term covers far more than arithmetic: mismatched SSNs on dependents, credit computations, and IRS data-entry of paper returns all fire CP11s. Math-error assessments skip the usual deficiency procedures, which makes the 60-day window critical: dispute within it and the IRS must abate and use normal procedures; miss it and you're stuck with the harder audit-reconsideration route.
You generally have 60 days — to request abatement of the math-error assessment with full rights. The respond-by date printed on your own notice always controls.
A 60-day math-error dispute letter is short and powerful: identify the change, state you request abatement under IRC 6213(b), attach the proof (SSN card copy, corrected computation). The IRS must then reverse and, if it still disagrees, issue a proper deficiency notice you can contest.