Audits are rarely lost on the law. They are lost on proof. Section 6001 requires you to keep records supporting every item on your return, and in an examination the substantiation burden sits with you — an expense the examiner cannot verify is an expense disallowed. This checklist is organised the way examiners work: issue by issue, each with its proof standard.
General information, not tax or legal advice. If your audit is already open, assemble what the letter asks for first, then use this checklist to find the gaps before the examiner does.
| Issue | Proof that meets the standard |
|---|---|
| Supplies, materials, inventory | Supplier invoices + proof of payment + inventory count records |
| Rent and utilities | Lease + cancelled checks or statements; a square-footage split if the space is shared |
| Contract labour | Contracts, invoices, and the Form 1099-NEC you filed for each contractor paid $600+ |
| Advertising | Invoices, screenshots/copies of the ads themselves, platform statements |
| Repairs vs improvements | Contractor invoices describing the work in enough detail to show repair, not capital improvement |
Travel, vehicle and meal expenses live under heightened substantiation: estimates and after-the-fact reconstructions routinely fail, and no Cohan-style estimation saves a §274(d) item — without the records, the deduction is lost, however plausible the amount. Publication 463 is the governing guide. For each trip you need four elements — amount, time (date), place, and business purpose:
Audits of the EITC, child credits and head-of-household status run on the Form 886-H worksheets — the CP75 guide covers the notice itself. The proof set:
| Records | Keep for |
|---|---|
| Most return-supporting records | At least 3 years from the date you filed the return (the assessment window) |
| Records for a year with substantial-omission exposure (more than 25% of gross income omitted) | 6 years from filing |
| Employment tax records | At least 4 years after the tax became due or was paid, whichever is later |
| Property and basis records | Until the limitations period expires for the year you sell or dispose of the asset |
| Records for a year you never filed, or a fraudulent return | Indefinitely — there is no limitations period (see how far back the IRS can audit) |
What documents do you need for an IRS tax audit? The records that support the items on your return: information returns (W-2s, 1099s, K-1s), bank statements for all accounts so deposits reconcile to reported income, and for each deduction both legs of proof — a document showing payment and a document showing business character (invoice, contract, log). Credits and dependents run on the Form 886-H document set; travel and vehicle items need the §274(d) records above; your letter names the specific items.
How do you know the IRS received your response or document? Use a channel that gives you proof, and keep it: the Document Upload Tool’s confirmation, a fax confirmation sheet, or certified mail with return receipt. Keep a complete copy of everything you sent with it — the response-letter page covers channels and proof in full.
How long should I keep tax records in case of an audit? Match the record to the clock: most return records 3 years from filing; 6 years where a substantial omission of income is possible; employment-tax records at least 4 years after the tax became due or was paid; property and basis records until the limitations period expires for the year you sell the asset; and records for a fraudulent or never-filed year indefinitely. The table above uses these same anchors.
What happens if you don’t have receipts for an IRS audit? Items you cannot substantiate are normally disallowed — the burden of proof is yours (§6001). Rebuild what you can from third parties: bank and card records, supplier copies, calendars and appointment books. But know the hard edge: for §274(d) items (travel, meals, vehicle use), estimates and reconstructions routinely fail and no Cohan-style estimation applies — those deductions stand or fall on contemporaneous records. Never manufacture documents — a false record turns a civil adjustment into a fraud problem.
Sources: IRC §§6001, 162, 170(f)(8), 274(d); IRS, “How long should I keep records?” and recordkeeping guidance (irs.gov); Forms 886-H and 8283 instructions. Currency verified 2026-10-23.