If you only get to run one test on a seller's numbers, run this one. A proof of cash checks whether the money the seller says the business earned actually showed up in the bank. It sounds basic, and it is, which is exactly why it works so well.
Quick answer: A proof of cash ties together what the books say the business earned, what the tax returns say, and what actually landed in the bank accounts for the same period. Small gaps are normal and usually have a boring explanation, like timing, transfers, or sales tax. Large or unexplained gaps are one of the clearest early warnings that the earnings behind your purchase price may not be real.
What is a proof of cash?
Accountants use the term a few different ways, but in a quality of earnings (QoE) review it usually means this: take every deposit into every business bank account for each month, strip out the deposits that are not revenue, and compare what is left to the revenue on the profit and loss statement. Then compare the yearly totals to the tax return.
The classic version also checks the other side of the ledger. Start with the opening bank balance, add all deposits, subtract all withdrawals, and you should land on the closing balance. Do the same math on the books. If the two line up, the books reflect reality. If they don't, someone has to explain why.
Why this test matters more than the P&L
- A P&L is something a person prepared. It can be adjusted, reclassified, or just plain wrong. A bank statement is a third party record that is much harder to massage.
- Small business books are built for taxes, not buyers. Many sellers run cash basis, some run accrual, and a few switch between the two depending on the year.
- Everything else sits on top of revenue. Add-backs, normalized earnings, and the multiple you pay only mean something if the revenue underneath is real. A proof of cash tests the foundation before you build on it.
How a proof of cash works, step by step
- Collect statements for every account the business touches. Checking, savings, credit cards, and the payment processors and platforms that pay out to the bank (Stripe, Square, PayPal, Shopify Payments, Amazon, a merchant account). Include any personal account the seller admits, or you suspect, was used for business.
- Total the deposits by month.
- Remove deposits that are not revenue. Transfers between the seller's own accounts, loan proceeds, owner contributions, insurance payouts, vendor refunds, and sales tax collected from customers.
- Adjust for timing. Customer deposits received before the work is done, invoices sent but not yet paid (accounts receivable), and payouts that land a few days after the sale.
- Compare to reported revenue, month by month, and then to the tax return for the year.
- Chase down every difference that is not obviously timing. This is where the real work is.
What it looks like in practice
Here is a simplified full year for two businesses that both report $1,200,000 of revenue. The numbers are made up for illustration.
| Business A | Business B | |
|---|---|---|
| Reported revenue (books) | $1,200,000 | $1,200,000 |
| Total bank deposits | $1,310,000 | $1,155,000 |
| Less non-revenue deposits (transfers, owner cash, loan proceeds) | ($105,000) | ($105,000) |
| Adjusted deposits | $1,205,000 | $1,050,000 |
| Adjusted deposits minus reported revenue | $5,000 | ($150,000) |
| Gap as a % of reported revenue | 0.4% | 12.5% |
Business A is fine. A $5,000 difference on $1.2 million is the kind of thing timing explains. Business B needs answers. Maybe a big chunk of invoices never got paid. Maybe revenue was booked that never happened. Maybe some deposits went to an account nobody showed you. Each of those explanations leads to a very different deal.
What the gaps usually mean
When reported revenue is higher than deposits
- Revenue was booked but the cash never arrived (uncollected receivables).
- Revenue was recorded early, or padded, ahead of a sale.
- Customers are paying into an account you have not seen.
- A big timing swing at year end.
When deposits are higher than reported revenue
- Money that is not revenue is sitting in the sales line, like loans, owner contributions, or transfers.
- Customers paid a deposit for work that has not been done yet, so the revenue belongs to a later period.
- The seller never recorded some revenue. That creates its own tax problem and its own credibility problem.
- Sales tax collected from customers is mixed into deposits.
Then there is cash that never goes to the bank. If a seller tells you a chunk of sales are cash that never got deposited, treat that as a red flag, not a selling point. A lender can't count money it can't see, and you can't verify it.
Why SBA lenders care
On SBA financed deals, lenders underwrite on cash flow, so they care a lot about whether the cash flow is real. The SBA's updated procedures (SOP 50 10 8.1, effective October 1, 2026) now require an independent QoE on qualifying acquisitions with a purchase price of $3 million or more. Accounting firm write-ups of the new rule describe cash proof and reconciling earnings to filed tax returns among the procedures a QoE is expected to cover. We break down the full rule in our SBA QoE requirement guide.
Below $3 million the rule does not require a QoE, but lenders can still ask for one, and a clean proof of cash makes underwriting easier either way. Every lender has its own approach, so ask yours what it wants to see before you commit to a timeline.
What buyers can do before the QoE starts
- Ask for statements for every business account, plus credit cards and payment processors, early. Slow or partial answers tell you something.
- Ask the seller directly whether any business money touches a personal account. It is much better to hear it now.
- Get the sales reports from the POS or platform that generates the sales, so deposits can be matched to real transactions.
- Ask for a list of loans, owner injections, and one-time deposits so they don't get mistaken for revenue.
- Be wary of a seller who will share a P&L but not bank statements. If the seller is stalling on documents, our guide on what to do when a seller won't provide documents covers your options.
Common questions
Is a proof of cash the same as an audit?
No. An audit is a broader assurance engagement on a company's financial statements. A proof of cash is one procedure that tests whether reported revenue is supported by actual deposits. It is often done as part of a QoE. For the full comparison, see QoE vs. audit.
How many months of bank statements do I need?
Usually the same period as the financials being analyzed, which for a QoE is typically two to three years plus the current year to date. Matching month by month is what surfaces the patterns.
Can a proof of cash catch everything?
No. It tests whether the money went in. It can't tell you whether the revenue will repeat, whether customers are concentrated, or whether an add-back is legitimate. That is what the rest of the QoE is for.
What if the business takes a lot of cash payments?
It is doable but harder. Compare deposits against POS data, invoices, and tax filings, and treat any cash that was never deposited as unverified until someone proves otherwise.
Bottom line: Bank statements are the closest thing a small business has to a neutral witness. Make sure the revenue story and the bank story match before you pay a multiple on either one.
Want someone to check the cash side before you commit?
Every ClearView QoE starts with the seller's financial statements, tax returns, and bank statements, and includes a tax return reconciliation. CPA-reviewed, fixed fee, 10 business days or less.
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