IRS CP75 / Letter 566 Notice: Correspondence Audit — Documents Requested
A CP75 (or Letter 566) is a correspondence audit: the IRS is holding part or all of your refund and asking for documents to prove specific items — most often the Earned Income Credit, dependents, or filing status.
Deadline calculator
The CP75 / Letter 566 clock runs from the date printed on the notice — not the day you opened it.
Estimate only, based on the standard 30-day CP75 / Letter 566 window. Your notice controls — always use the specific date printed on it.
What a CP75 / Letter 566 actually means
This is a real audit, conducted by mail, but narrow: the IRS lists exactly which items it wants verified. Typical targets are EITC eligibility, head-of-household status, dependents' residency, and business income/expenses for Schedule C filers.
Well-organized documentation wins these. School and medical records showing a child's address, birth certificates, custody papers, receipts, and mileage logs are the usual proof. Weak or late responses turn refundable credits into disallowances plus possible multi-year bans.
What to do, step by step
- 1Read exactly which items are being examined — respond to those, thoroughly.
- 2Gather primary documents (school/medical/lease records for dependents; ledgers and receipts for Schedule C).
- 3Send copies (never originals) by the deadline, with the response page on top.
- 4If you need more time, call the number on the notice and request it before the deadline.
- 5If the credits are denied and you disagree, you can appeal — but the strongest move is a complete first response.
Common questions
Why is the IRS auditing my Earned Income Credit?+
EITC has the highest error rate of any credit, so the IRS verifies eligibility aggressively — especially residency of qualifying children. Documentation showing the child lived with you (school, medical, lease records) usually decides the case.
What if I can't get the documents in 30 days?+
Call the number on the notice and ask for an extension — the IRS routinely grants more time when you engage before the deadline.
Received a CP75 / Letter 566? Get it handled.
Talk to a tax specialist about your notice — free, no pressure, no judgment.