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.
How to recognize a real CP75 / Letter 566
IRS Examination sends the CP75 to start a correspondence (mail) audit of refundable credits and filing status. It holds back the Earned Income Credit and Additional Child Tax Credit parts of the refund, and sometimes part of the refund tied to the Premium Tax Credit, until the audit ends.
- The heading reads "We're auditing your [year] Form 1040" and "You need to send supporting documentation."
- The left column says the IRS is holding the EIC and/or ACTC portions of your refund, and possibly part of it because of the Premium Tax Credit. It also says you must respond within 30 days of the notice date.
- An "Audit items that require supporting documentation" table lists each item, with a matching enclosure: Form 886-H-EIC for a qualifying child's relationship, age, and residency; Form 886-H-HOH for head of household status; Form 14950 for the Premium Tax Credit.
- The last page is a Response form with checkboxes for the items your documents support.
- It includes Publication 3498-A (The Examination Process), which explains your appeal rights.
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.
Illustrative example
Example: Proving a child's residency in a CP75 audit
Illustrative scenario: Keisha claimed her 6-year-old nephew for the EIC and filed as head of household, expecting a $7,200 refund. She gets a CP75 dated February 20 holding $5,900 (the EIC and ACTC portions) and listing two items: Earned Income Credit and Filing Status.
She reads the enclosed Form 886-H-EIC and 886-H-HOH to see which documents count. Within two weeks she collects a letter on school letterhead showing the nephew's address, his doctor's records at the same address, her lease, and birth certificates showing how she and her nephew are related. She checks both boxes on the Response form and uploads everything together through the IRS document upload tool.
The IRS says it needs at least 30 days to review. In April she gets a letter closing the audit, and the held refund arrives. If her proof had covered the EIC but not head of household, she would have gotten an audit report changing only that item, with the right to appeal.
Names and numbers are made up to show how this notice typically plays out.
Mistakes that make a CP75 / Letter 566 worse
- Proving the relationship but not the residency. The EIC form asks you to show the child met the relationship, age, and residency tests, and missing residency proof is the most common gap.
- Answering only one of the items listed. If the notice lists EIC and Filing Status, each needs its own documents and its own checkbox on the Response form.
- Sending documents in separate batches. The IRS asks you to send everything together, in readable form, with the Response form.
- Missing the 30-day window without calling. The notice tells you to call if you can't get your documents together in time. A missed deadline with no call means the items are disallowed.
- Skipping the 886-H forms. They list exactly which documents the IRS accepts, such as school, medical, or landlord records, and guessing wastes your one best chance.
What happens if you ignore a CP75 / Letter 566
If the IRS doesn't get your documents within 30 days, it disallows the audited items and sends an audit report showing the proposed changes, including any extra tax, penalties, and interest. The held portion of your refund isn't released.
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.
Checked against IRS primary sources — see how we source these guides. You can verify any notice directly at IRS.gov. The dates and instructions printed on your specific notice always control. Official IRS explanation: Understanding your CP75 notice (IRS).
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