Financial Due Diligence When Buying a Service Business: What to Test Before You Sign

Don't use financial due diligence to confirm the seller's numbers are honest. Use it to answer a harder question: will the cash this business produced last year still show up after the seller walks out? In a service business, the seller is often the head of sales, the senior delivery lead, and the reason the top client stays. A generic diligence checklist doesn't test for that.

Run five tests in this order. Each one either changes the earnings number you're paying for or changes the deal structure. If a test does neither, it's paperwork.

This is for a buyer, or an owner buying a competitor, looking at a $2M–$15M revenue service business with an LOI signed or about to be.

The five tests at a glance

The order matters. There's no point debating add-backs on revenue that never hit the bank.

Test 1: Prove the cash before you study the profit

Reconcile bank deposits to reported revenue, month by month, for the trailing twelve months and the last two fiscal years. Then reconcile disbursements to expenses.

This isn't a nice-to-have. When an SBA 7(a) loan funds an acquisition with a business purchase price of $3 million or more, SBA SOP 50 10 8.1, effective October 1, 2026, requires the lender to obtain a quality of earnings report that includes a cash proof covering the trailing 12 months and the last two fiscal years. The same SOP requires lenders to verify the seller's financial information against IRS tax transcripts. If a lender won't trust a P&L without bank statements and transcripts, a buyer shouldn't either.

What you're looking for:

• Revenue booked but never deposited, or deposits with no invoice behind them.
• Cash-basis books that hide a receivables build or a deferred-revenue liability.
• Tax-return revenue lower than P&L revenue. That's a question for the seller, and a question for your purchase agreement's tax indemnity.

Test 2: Audit every add-back like it's a price increase

It is one. At an illustrative 4.5x multiple, each $100,000 of accepted add-backs adds $450,000 to the price.

Ask for the general-ledger detail and an invoice for each adjustment. Sort them into three piles:

• Accept. Owner salary above market, a documented lawsuit settlement, a one-off office move.
• Accept with proof. Owner's family on payroll who'll leave at close, and personal expenses run through the business.
• Reject. Recruiting fees that happen every year, "one-time" software migrations that happen every other year, and client entertainment relabeled as personal.

The EBITDA recast guide covers how sellers build these adjustments. Your job is to undo the ones that don't hold.

Test 3: Price the jobs the seller does for free

This is the test that matters most in a service business. The seller takes a $120,000 salary and works 55 hours a week as CEO, head of sales, and relationship lead on the top five accounts. After close, you'll need to pay at least one person to do part of that.

List every role the seller performs. Estimate the market cost to replace each one. Deduct the difference between that cost and what the seller is paid in the P&L.

Then check delivery labor against revenue. Bennett uses a labor efficiency ratio, revenue ÷ all delivery labor cost including contractors, with 3.5x as a minimum, as one of the seven ratios read in order. If the target only clears 3.5x because the seller bills 1,500 hours a year personally, that efficiency leaves with the seller.

Before you price someone else's business, know what your own numbers would look like to a lender. The Profit & Tax Leak Check flags the margin, payroll, and tax leaks in your current company that would weaken your debt capacity for an acquisition.

Test 4: Test whether the revenue survives the handover

Build a revenue-by-client-by-month table for 24 months. Then answer four questions:

1. What share of revenue comes from the top client and the top five?
2. How much of that revenue is under a contract, and can the contract be assigned to a new owner, or terminated on a change of control?
3. Who owns the relationship: the firm, or the seller personally?
4. When does each major contract renew relative to your closing date?

A client at 22% of revenue on a 30-day termination clause, renewing four months after close, isn't an EBITDA adjustment. It's a structure problem. Solve it with an escrow, a price holdback, or a buyer rebate if the client leaves. Be careful with earnouts if you're borrowing: SBA SOP 50 10 8.1 prohibits seller earnouts in 7(a) change-of-ownership deals but allows buyer rebates based on business performance.

Test 5: Count the cash the business owes back

Service businesses often collect before they deliver. Prepaid retainers, annual contracts billed upfront, and client deposits are cash the seller has already received for work you'll have to do. Accrued bonuses and unpaid payroll taxes fall in the same bucket.

Two mechanisms protect you:

• A working-capital peg that sets the normal level of receivables minus payables delivered at close. The peg math for service businesses shows how unbilled work and deferred revenue get disputed.
• A debt-like items schedule that deducts obligations such as deferred revenue and unpaid bonuses from the price. The debt-like items ledger lists the ones that are easy to miss.

A worked example: what the five tests do to the price

Here's a hypothetical $6.5M-revenue marketing agency. The seller presents $1.2M of adjusted EBITDA, and the LOI is built at an illustrative 4.5x, or $5.4M.

At the same 4.5x, the supported price is $4.32M. That's $1.08M below the LOI.

Tests 4 and 5 don't change EBITDA here, but they change the deal. The top client is 22% of revenue on 30-day terms, which justifies holding back part of the price. There's also $400,000 of prepaid retainers, which should come off the price as a debt-like item or be delivered as cash at close.

Notice that the buyer didn't need a forensic audit to find this. They needed bank statements, the ledger, a client revenue table, and an honest list of what the seller does all day.

What diligence costs and who does it

Diligence costs depend on scope: how many years you test, how many entities are involved, whether the books are cash or accrual, and how many add-backs need support. A full quality of earnings report is the deepest version. For SBA-financed buyers, SOP 50 10 8.1 allows money the buyer spends on financial due diligence reports to count toward the required equity injection.

Whoever does the work, the buyer still owns the decision. Your accountant can tell you the add-backs don't reconcile. You have to decide whether that kills the deal or changes the price.

The next number to run

Take the seller's adjusted EBITDA and run it through tests 1–3. If the diligence-adjusted figure still supports your offer and your lender's coverage requirement, which our acquisition debt-capacity model sets out, move to tests 4 and 5 and negotiate structure. If it doesn't, re-price before you spend money on legal documents.

Fractional CFO support can run that rebuild with you, or sit beside your QoE provider and turn the findings into price and structure. If you're financing the purchase partly from your existing company's cash flow, run a Leak Check on that company first, because the acquisition will be underwritten on both sets of numbers.