Picture this: an IRS notice lands in your mailbox questioning $18,000 of business deductions. You reach for your proof, and your stomach drops. The thermal-paper receipts faded to blank months ago. The phone with all your photos died over the summer. Your old bookkeeping app stopped syncing in March. Every dollar you claimed is real — you know it — but can you prove it?
Most business owners assume missing receipts mean automatically lost deductions. Usually, that assumption is right. But not always. For nearly a century, courts have applied a doctrine called the Cohan rule: when you can show you genuinely spent the money on your business but cannot pin down the exact amount, a judge may estimate the deduction instead of disallowing it entirely.
This is a backup parachute, not a flight plan. It only works in some situations, it never works for certain categories of expenses, and the estimate routinely comes in lower than what you actually spent. Here is how the rule works, where it stops working, and how to rebuild a credible file when your receipts are gone.
What the Cohan Rule Actually Says
The rule comes from a 1930 federal appeals decision involving a famous Broadway entertainer of the era who kept terrible records. He clearly spent large sums traveling and staging shows, but he had almost no documentation. The court refused to disallow everything: when it is certain that money was spent on the business, the court said, demanding absolute precision would punish honest taxpayers for bad bookkeeping rather than dishonesty. So the court estimated.
Three principles from that decision still govern today:
- You must prove the expense happened. The rule rescues uncertain amounts, not uncertain expenses. If you cannot convince anyone the spending occurred at all, there is nothing to estimate.
- You must supply some credible basis for the number. Bank statements, calendars, testimony, industry averages — the court needs a starting point. A number pulled from thin air gets you nothing.
- The guess goes against you. The opinion famously says the estimate should weigh heavily against the taxpayer whose own sloppy records created the problem. Expect the allowed amount to land well below what you claim.
In short: the Cohan rule converts "no proof, no deduction" into "thin proof, partial deduction" — but only if you give the decision-maker something solid to work with.
Where the Cohan Rule Does Not Work: Section 274(d)
This is the part that surprises people. Congress carved out four categories of expenses where estimation is flatly forbidden. Under Section 274(d), no deduction is allowed for these unless you substantiate each one with adequate records or corroborating evidence:
- Travel expenses (flights, hotels, rental cars, and travel meals)
- Entertainment expenses (to the limited extent any remain deductible)
- Business gifts
- Listed property — assets that lend themselves to personal use, such as passenger cars and other vehicles placed in service for business
The temporary regulation is explicit that Section 274(d) supersedes the Cohan rule. If your missing receipts are hotel folios, airfare confirmations, client-dinner bills, or vehicle records, no court can estimate them for you. They are disallowed, full stop.
For each of these expenses, the regulations demand proof of three elements: the amount, the time and place, and the business purpose (plus the business relationship for gifts and entertainment). That means an "adequate record" — an account book, diary, log, or similar record made at or near the time of the expense — backed by documentary evidence such as receipts or paid bills.
Two practical details matter here:
- Lodging always needs a receipt. There is no minimum threshold for hotel stays while traveling away from home.
- The $75 receipt threshold. For other Section 274(d) expenses, documentary evidence like a receipt is generally required for any expenditure of $75 or more. Below $75, a timely log entry showing amount, date, place, and business purpose can suffice — but transportation charges are excused from the receipt requirement only when a receipt was not readily available.
The takeaway: your reconstruction energy should go toward ordinary operating expenses — supplies, software, contractors, rent, utilities, advertising — where estimation is legally possible. For travel, gifts, and vehicles, prevention is the only strategy, because no cure exists.
What Counts as Reconstruction Evidence
Courts look for corroboration — independent pieces that, fitted together, make your claimed amount believable. No single item below proves much on its own. Stacked together, they can carry real weight:
- Bank and credit-card statements. These establish that money left your accounts, when, and to whom. They are the foundation of almost every reconstruction.
- Calendars and appointment records. A calendar showing client sites, job locations, or supplier visits corroborates that trips and purchases had a business reason.
- Emails, texts, and messages. Order confirmations, project threads, contractor communications, and scheduling messages tie spending to specific business activity.
- Vendor and client confirmations. A supplier's duplicate invoice or a client's payment record can substitute for your lost copy. Many vendors will reissue invoices on request.
- Photos and files with metadata. Job-site photos, screenshots, and project files carry timestamps that anchor your timeline.
- Mileage and expense logs, even reconstructed ones. A log rebuilt now from calendars and statements is weaker than one kept contemporaneously, but it is far better than nothing.
- Your own credible testimony. Judges weigh whether your story is consistent, detailed, and plausible. Vague round numbers with no backup fail; specific, documented narratives succeed.
- Deemed-substantiation shortcuts. The IRS allows standard mileage rates and per-diem rates to stand in for the amount element of vehicle and travel costs. You still must prove time, place, and business purpose — but you do not need to reconstruct every gallon of gas or hotel breakfast.
Notice the pattern: every item answers either "did the money move?" or "was it for the business?" Your file needs both answers for every category you claim.
Why Bank Statements Alone Usually Lose
The single most common reconstruction mistake is printing twelve months of card statements, highlighting business-looking charges, and calling it done. Statements prove payment, but they almost never prove purpose. A $412 charge at a big-box store could be office supplies or a personal television. A restaurant charge could be a client lunch or a family dinner.
Courts have repeatedly held that statements without more do not establish the business purpose of an expense. The fix is annotation: for each highlighted charge, attach whatever shows why it was business — the project it belonged to, the client it served, the email thread that ordered it. A short written memo per category, prepared while memories are fresh, explaining your method ("all highlighted charges cross-referenced to the project calendar in Exhibit B") turns a pile of statements into an actual case.
How to Rebuild a Missing-Receipt File, Step by Step
If you are facing an audit — or just discovered your records have a hole — work through this playbook methodically:
1. Separate the salvageable from the doomed
Split your claimed expenses into two buckets: ordinary operating expenses (supplies, rent, software, contractors, advertising, utilities) where estimation is possible, and Section 274(d) expenses (travel, entertainment, gifts, vehicles) where it is not. Spend your reconstruction hours on the first bucket. For the second, gather whatever strict substantiation still exists and concede the rest early — credibility lost defending hopeless items infects your credible ones.
2. Pull every financial record available
Download full-year statements for every business bank account and credit card. Request missing months from the bank. Pull payment-processor histories (your card reader, online invoicing tool, and payment apps each keep their own records). Export accounting software data, even if it stopped syncing mid-year — partial ledgers still anchor amounts and dates.
3. Rebuild the calendar
Reconstruct where you were and what you worked on, week by week: scheduling apps, email timestamps, project management tools, client invoices with dates of service, and even phone location history. This timeline becomes the spine that every expense hangs on.
4. Re-request third-party proof
Contact your ten or twenty largest vendors for duplicate invoices. Landlords, insurers, software providers, and wholesalers can almost always reissue annual summaries. Each duplicate converts an estimated expense back into a documented one.
5. Write the methodology memo
For each expense category, write a plain-English page explaining what the expense was, how you reconstructed the total, and which exhibits support it. Example: "Office supplies, $3,840: monthly card charges at two office retailers, cross-referenced to studio lease showing continuous operation; duplicate annual summary from Retailer A attached." Sign and date it. A transparent method with acknowledged gaps beats confident round numbers every time.
6. Organize it like an examiner thinks
Group everything by tax-return line item, with a one-page summary per category on top and exhibits behind it. Number the pages. An examiner who can follow your file in twenty minutes is an examiner inclined to accept it.
The Expenses That Still Die Without Receipts
Be blunt with yourself about the casualties:
- Travel, entertainment, gifts, and listed-property costs without adequate records and documentary evidence — Section 274(d) allows no estimation.
- Lodging of any amount without a receipt or folio.
- Charitable contributions have their own statutory proof rules: cash gifts generally need a bank record or written receipt, and any single contribution of $250 or more needs a written acknowledgment from the charity. Courts will not estimate these either.
- Anything with no foundation at all. If the only evidence is your memory of a round number, the Cohan rule cannot help — there is no basis for an estimate.
Knowing what is already lost keeps you from spending weeks defending the indefensible while reconstructible deductions sit unorganized.
Stop Losing Receipts in the First Place
The Cohan rule exists because a court in 1930 felt sorry for a taxpayer with no records. Modern courts feel considerably less sorry — you carry a scanner, camera, and accounting system in your pocket. The entire doctrine is a warning: build a system where reconstruction is never necessary.
The system does not need to be elaborate:
- Capture at the point of sale. Photograph or forward every receipt the day money moves. Paper fades; phone photos in a backed-up folder do not.
- Log purpose immediately for travel and meals. Amount, date, place, business reason, and who was there — thirty seconds in a notes app satisfies the regulation that a lost receipt cannot.
- Reconcile weekly, not yearly. A fifteen-minute weekly review catches missing documentation while memories and vendor portals are fresh. Twelve months later, both are gone.
- Keep one ledger that ties everything together. When every receipt photo, statement line, and invoice maps to a single set of books, an examiner — or your future self — can trace any number back to its source in minutes.
This is where your bookkeeping setup pays for itself. A plain-text ledger gives you a complete, searchable, version-controlled history of every transaction that no app shutdown or sync failure can take away, and pairing it with a simple folder of receipt scans means the "shoebox" is always organized. If you want to see what that workflow looks like in practice, the guides in /docs/ walk through transaction entry and reconciliation step by step, and /fava/ provides dashboards that make weekly reviews fast enough to actually do.
Keep Every Dollar You Deserve
Missing receipts do not have to mean missing deductions — but only if you understand the boundaries. Ordinary business expenses can be estimated when you prove they happened and give the court something credible to measure with. Travel, gifts, entertainment, and vehicle costs cannot; the law demands real records, and no judge is allowed to guess.
So rebuild what you can with statements, calendars, vendor duplicates, and an honest methodology memo — and then make sure you never need the Cohan rule again. Beancount.io offers plain-text accounting that keeps your entire financial history transparent, version-controlled, and ready for scrutiny — no black boxes, no lost syncs, no faded ink. Get started for free and give every future deduction the paper trail it deserves.
