Sometimes — and which side of one specific line the expense falls on decides it.
The two buckets
Bucket A — ordinary business expenses (supplies, materials, subcontractors, professional fees, rent, utilities, software, advertising, insurance, repairs). Under the Cohan rule (Cohan v. Commissioner, 39 F.2d 540 (2d Cir. 1930)), a court may approximate a deductible amount where it is satisfied the expense was genuinely incurred but the exact figure is undocumented. Three caveats matter: it is the court's discretion rather than your right, you still have to show the expense happened, and the approximation is made against the taxpayer whose records are at fault — so it lands conservative.
Bucket B — travel, meals, gifts, and listed property (listed property includes passenger automobiles, so mileage sits here). IRC §274(d) requires strict substantiation of the amount, the time and place, and the business purpose, and Treas. Reg. §1.274-5T(a) expressly supersedes the Cohan rule for these categories. No records means no deduction, no matter how honest the claim. Entertainment is generally not deductible at all post-TCJA.
So the useful exercise is sorting your at-risk deductions into those two columns. Real exposure is the Bucket B total, not the whole claim.
What still counts as proof, strongest first
- The contemporaneous receipt.
- Merchant confirmation emails / digital receipts — usually the richest untapped source, because almost all modern spend emails you a confirmation and nobody deletes them.
- Vendor duplicate invoices (suppliers and SaaS vendors will reissue; many retain 7+ years).
- Bank or card statements — these establish amount, date, and payee but not business purpose, which is what an examiner tests. Partial evidence, not a substitute.
- Calendar entries and contemporaneous notes — weak on amount, strong on business purpose. Pair with a statement line.
- Written reconstruction — permitted, weakest tier.
Recovering records
Work in this order: identify exactly which line items and which tax year are in scope → pull that year's bank and card statements → search email merchant-by-merchant against those statements → request vendor duplicates for the gaps → assemble by deduction line, not chronologically.
ExpenseBot automates the email step: it scans a connected Gmail account for receipts and writes them into a Google Sheet you own. It captures receipts into a spreadsheet — it does not prevent examinations and does not make records audit-proof.
Record retention (current IRS guidance)
- 3 years generally
- 6 years if you did not report income you should have and it exceeds 25% of the gross income shown on the return
- Indefinitely if you did not file a return, or filed a fraudulent one
Full write-up: https://www.expensebot.ai/blog/cohan-rule-no-receipts
Estimates — confirm with your tax professional.