What a proof of cash is and why buyers ask for one

When you’re evaluating a small business acquisition, you need to know whether the seller’s reported revenue actually made it to the bank. A proof of cash is exactly that: a reconciliation between the cash the seller claims to have earned and the deposits that appeared in the business’s bank statements. It sounds straightforward, but proof of cash due diligence is where many buyers discover material discrepancies—missing deposits, revenue timing issues, commingled personal funds, or undisclosed customer returns. Unlike a revenue audit, which examines whether sales were correctly recorded, proof of cash focuses on a single, objective question: did the claimed revenue hit a bank account?

The Core Purpose of Proof of Cash

Revenue figures on tax returns or profit-and-loss statements are declarations. A proof of cash is verification. It answers the buyer’s fundamental concern: are these numbers real cash, or adjustments and accruals that never landed in an account you can actually see?

In a full Quality of Earnings engagement with a licensed CPA firm, proof of cash is one component of several cross-checks on revenue. For a smaller acquisition under $5M in deal value, proof of cash often becomes the primary mechanism to validate top-line claims. The seller provides their financial records; you obtain the bank statements directly from the financial institution; you reconcile them line by line. If the deposits match the claimed revenue (after accounting for timing differences and legitimate adjustments), the revenue number passes the sniff test. If they don’t, you have a specific, documentable red flag.

How Proof of Cash Works: The Mechanics

A basic proof of cash reconciliation follows this structure:

• Take the seller’s reported revenue for a specific period (usually a full fiscal year or the trailing twelve months).
• Adjust for timing differences: accrued revenue not yet deposited, deposits received in advance (deferred revenue), and legitimate timing gaps between the sale date and the deposit date.
• Account for non-cash revenue: barter transactions, equity compensation, or other items recorded as revenue but never hitting the bank.
• Reconcile to actual deposits: pull the business bank statement for the same period and sum all deposits classified as customer revenue (excluding loan proceeds, capital contributions, or inter-account transfers).
• Investigate gaps: any material difference between adjusted revenue and total deposits requires an explanation from the seller and supporting documentation.

Here’s a worked example. Imagine a service business with $500,000 in claimed revenue for 2025. The bank statements show $475,000 in customer deposits over the same twelve months. That’s a $25,000 gap. Before raising an alarm, you adjust:

• $8,000 in invoices issued in December 2025 but not collected until January 2026 (accrued revenue).
• $3,000 in customer prepayment received in November 2025 for services delivered in January 2026 (deferred revenue to subtract).
• $1,500 in barter transaction recorded as revenue but no cash received (non-cash adjustment).

Adjusted revenue: $500,000 + $8,000 – $3,000 – $1,500 = $503,500. Hmm, now the gap is larger. This signals the seller to produce invoices, customer communications, and delivery evidence for the $8,000 accrual, proof that the barter was legitimate, and documentation of the $3,000 deferral. Once you verify those adjustments are sound, the remaining discrepancy ($503,500 minus $475,000 = $28,500) needs a home—usually uncollected receivables, bad debts written off, or customer returns not reflected on the P&L.

The seller should be able to show you aged accounts receivable, bad-debt write-offs, and credit memo records that account for every dollar. If they can’t, you’ve identified a material inconsistency in their financial reporting, and that gets reflected in your acquisition offer.

Common Red Flags and Edge Cases

Proof of cash due diligence often uncovers patterns that wouldn’t be obvious from tax returns alone.

Commingled personal deposits. A seller deposits customer checks into a personal account, then moves funds to the business account in batches. Bank statements show the business received $400,000, but the seller’s P&L claims $450,000. Ask for documentation of all deposits to personal accounts that relate to the business, and trace them into the business account. You’re looking for a complete trail, not just a reconciliation.

Credit card and payment processor deposits. Many businesses receive revenue through Stripe, Square, PayPal, or merchant accounts. These processors deposit net of fees and chargebacks, often on a rolling or weekly basis. The seller’s financial records may record gross revenue; the bank statements show net deposits. Make sure you’re comparing apples to apples. Request the processor settlement reports to bridge gross revenue to the net deposits you see in the bank.

In-kind contributions or owner transfers. Owners sometimes “loan” personal funds to the business or contribute equipment. If these are recorded as revenue rather than capital contributions or loans, proof of cash will catch it. Similarly, funds transferred between owner accounts or business accounts within the same holding structure can look like revenue if not carefully labeled.

Undeposited checks and cash. A seller might claim they have uncollected checks sitting in a drawer. Ask to see them, verify they’re dated within the measurement period, and understand why they weren’t deposited. Undeposited checks that should have been deposited are a red flag for either poor bookkeeping or intentional timing manipulation.

Multiple bank accounts. Some businesses operate several checking accounts or savings accounts. A complete proof of cash must capture deposits across all accounts the business controlled. Sellers sometimes exclude a second account “by mistake,” which creates an artificial revenue gap.

Conducting Proof of Cash Due Diligence: A Buyer’s Checklist

Phase 1: Preparation

• Define the measurement period (usually TTM or full tax year).
• Obtain the seller’s P&L or tax return showing the revenue figure you’re testing.
• Request a list of all bank accounts held by the business during the measurement period, including account numbers and institutions.
• Request the seller’s accounts receivable aging and bad-debt write-off records.

Phase 2: Bank Statement Review

• Obtain bank statements directly from each financial institution (or through your accountant). Do not rely on statements the seller provides; go to the source.
• Classify each deposit as either customer revenue, loan proceeds, capital contributions, inter-account transfers, or other non-revenue items.
• Sum all customer revenue deposits for the full period.

Phase 3: Reconciliation

• List all timing adjustments (accrued revenue, deferred revenue, non-cash items).
• Calculate adjusted revenue: seller’s reported revenue ± adjustments.
• Compare adjusted revenue to total customer deposits.
• Document every line item and adjustment in a simple spreadsheet.

Phase 4: Variance Investigation

• For any variance over 5% or exceeding $10,000 (whichever is lower), request seller documentation.
• Ask for specific invoices, customer communications, or account statements to support accruals or deferred revenue claims.
• Request aged receivables and bad-debt schedules.
• Investigate credit memos or returns that reduced cash collections.
• Confirm that any unusual deposits or transfers have a documented business purpose.

Phase 5: Conclusion

• Determine whether variances are explained, immaterial, or material enough to affect valuation.
• Document your findings in a one-page summary with supporting schedules.
• Use this to inform normalized EBITDA adjustments and negotiating leverage in the LOI.

Proof of Cash in Context of Normalized Earnings

Proof of cash due diligence is a starting point, not an ending point. Once you’ve verified that claimed revenue actually hit the bank, you still need to assess the quality and sustainability of that cash. Is it from recurring customers or one-time projects? Does it depend on a single customer? Is the business growing or declining?

Normalized EBITDA calculations rely on accurate, verified revenue figures as their foundation. If proof of cash uncovers material discrepancies in the seller’s revenue reporting, those discrepancies ripple through every valuation metric you calculate. A platform like Outsourcing Processing can help you organize and cross-check revenue data alongside normalized add-backs and adjustments, but the underlying proof of cash itself is your responsibility as the buyer.

Work with your CPA or bookkeeper to structure the reconciliation cleanly. If variances emerge, get them in writing from the seller and attach the supporting documentation to your acquisition file. If you proceed to close, these records become part of your post-closing true-up and working capital adjustment calculations.

Proof of cash due diligence is methodical work, but it’s the most direct way to answer whether a business’s top-line revenue claims are grounded in actual cash receipts. Start with bank statements, build your reconciliation systematically, and chase every material variance to its source. The time you spend here prevents expensive surprises after close.

This article is educational and does not constitute M&A, investment, or accounting advice — confirm findings with a licensed CPA or M&A advisor before making an offer.

Frequently Asked Questions

What’s the difference between proof of cash and a revenue audit?

Proof of cash reconciles reported revenue to actual bank deposits—it’s a mechanical verification. A revenue audit examines whether sales were correctly recorded in the first place (invoices issued, customer contracts, delivery evidence). Proof of cash answers “did the money arrive?” A revenue audit answers “was the sale legitimate?” Both matter, but proof of cash is usually faster and cheaper for smaller deals.

Can I use the seller’s bank statements they provide, or do I need to get them directly from the bank?

Always obtain statements directly from the financial institution. Seller-provided statements can be altered, incomplete, or exclude accounts. Your CPA can request official statements on your behalf, or you can contact the bank yourself. This is non-negotiable for any material acquisition.

What’s an acceptable variance between reported revenue and deposited cash?

Timing and accrual differences are normal. A 2–5% variance explained by documented accruals, receivables, or legitimate non-cash items is typical. Anything larger or unexplained warrants investigation. The threshold depends on your risk tolerance and deal size—a $10,000 gap in a $500,000 revenue business is material; in a $5M business, it may not be.

How do I handle revenue the seller deposited into a personal account instead of a business account?

Request the seller produce deposits into personal accounts that relate to the business, along with evidence of when funds were transferred to the business account. Build a complete audit trail from the initial deposit (personal or business) through to the business checking account. This is common in sole proprietorships and requires careful documentation but is straightforward to reconcile if the seller cooperates.

Does proof of cash catch revenue I should add back as an add-back for normalized earnings?

Not directly. Proof of cash verifies that reported revenue hit the bank. Normalized earnings adjustments (adding back owner compensation, one-time items, or non-recurring expenses) are separate analyses. However, if proof of cash uncovers that certain revenue is one-time or unsustainable (a large customer advance, a one-off project), that finding informs whether you should adjust normalized EBITDA to exclude it.

This article is educational and does not constitute M&A, investment, or accounting advice — confirm findings with a licensed CPA or M&A advisor before making an offer.

For a faster alternative to a traditional QoE engagement, see IncomeReady for M&A Buyers.