United States / Blog / The five bookkeeping mistakes that surface in every due diligence
United States · noteThe five bookkeeping mistakes that surface in every due diligence
Diligence doesn't find fraud. It finds discipline gaps.
Most founders picture due diligence as a hunt for something hidden. In practice a quality-of-earnings review is closer to an audit of your habits: does the general ledger tell the same story every month, or does it get rebuilt from bank statements right before a raise closes?
A buy-side team, or an investor's CPA firm running QoE ahead of a term sheet, pulls twelve to thirty-six months of trial balances and looks for the same handful of patterns. None of them require bad intent. All five below come from ordinary shortcuts that compound because nobody circled back to fix them.
The suspense account that became a graveyard
A suspense or "clearing" account is a legitimate parking spot: a deposit lands before you know which invoice it settles, or a bill posts before the vendor is coded. The mistake is never clearing it. Eighteen months in, the account holds forty small transactions nobody can explain without opening the original bank feed.
To a reviewer this reads as an unreconciled balance sheet, and an unreconciled balance sheet means the income statement above it can't be trusted at face value either. Suspense accounts are a fine tool. The fix is a standing rule that nothing sits in one past the month it was opened, with a named owner who closes it out at each monthly close rather than at fundraise time.
Revenue booked at invoice, not at delivery
The most common revenue-recognition gap in early-stage companies is timing: revenue gets recognized when the invoice goes out, not when the performance obligation is actually satisfied. For a services company that bills a project in full on day one but delivers over three months, that pulls revenue forward and misstates every interim period in between.
Under ASC 606, the FASB standard that governs revenue from contracts with customers, revenue is recognized as control of the promised good or service transfers to the customer — not on the invoice date. For SaaS and retainer businesses this usually means spreading an annual contract over the service period rather than recognizing it on the invoice date; for project work it means tying recognition to milestones or percentage of completion. A reviewer will pull ten to twenty invoices at random and trace each one back to the underlying contract terms — if invoice date and recognition date are always the same, that's the tell.
The revenue-recognition position itself is a call for your CPA firm, not something a bookkeeping process decides on its own — but the mechanism of tying each invoice to a documented delivery date is what makes that call auditable later.
Founder expenses running through a personal card
Paying a vendor from a personal card because the company card was declined, or because reimbursement felt faster than waiting for a business account to fund — it happens in the first year of almost every company. The problem is what it does to the books six quarters later: nobody can tell, from the GL alone, which expenses are real operating cost and which are a founder float that was never cleanly reimbursed.
IRS guidance frames a deductible business cost as one that is ordinary and necessary to the trade, and a mixed personal-and-business account makes that harder to substantiate on every line. In diligence, a reviewer treats every personal-card transaction as a related-party item until proven otherwise, which slows the whole review down even when every dollar was legitimate.
Clean looks like a business checking account and card from week one, a reimbursement queue for the rare exception, and zero balance in any "due to shareholder" line by the time a QoE review starts.
Payroll that doesn't tie to the general ledger
Payroll is run through a processor, the processor's numbers get summarized into a single monthly journal entry, and that entry drifts from what was actually filed with the IRS — a bonus posted in the wrong quarter, a contractor reclassified after the fact, a benefits deduction that changed mid-year without a corresponding GL adjustment.
Form 941, the employer's quarterly federal tax return, exists precisely to reconcile what was withheld from employees and deposited with the IRS each quarter. A reviewer runs the same reconciliation against your GL: total wage expense per the books should tie to total wages per the filed 941s for the same period. When it doesn't, every payroll-adjacent number — burn, headcount cost, gross margin on a services business — gets a question mark next to it until someone explains the gap.
The fix is mechanical: reconcile payroll to the GL every quarter when the 941 is filed, not once a year at tax time.
Deferred revenue that was never tracked as a liability
A customer pays for a year up front. Cash goes up, and — if revenue is being recognized at invoice rather than over the service period — so does reported revenue, all in the month of payment. What should have landed on the balance sheet as deferred revenue (a liability representing service still owed) never gets booked at all.
This is the same ASC 606 mechanism as the invoice-timing mistake above, but it shows up as a missing balance sheet line rather than a misstated income statement one — which is often harder to catch without someone asking the specific question. For a subscription or retainer business, an untracked deferred-revenue balance means the company is reporting cash-basis results as though they were accrual, and a reviewer building a normalized P&L has to reconstruct the whole schedule from contracts rather than pull it from the books.
Clean looks like a standing deferred-revenue schedule, one row per active contract, updated every time cash comes in — not rebuilt from scratch when a term sheet shows up.
What the clean version has in common
None of these five require sophisticated accounting. They require the same close discipline applied every month instead of reconstructed under deadline pressure: suspense accounts cleared on a cadence, revenue tied to a delivery date rather than an invoice date, one bank account for the business, payroll reconciled against the filed 941 each quarter, and a deferred-revenue schedule that's always current.
A reasonable test is whether last month's close would survive being handed to a stranger with no context. If the answer is "not without me walking them through it," that's the gap a QoE review will find — better to find it before someone else does.
Reading about it is optional. The books aren’t.
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