After three decades of reviewing books handed over from other bookkeepers, the same handful of mistakes turn up again and again. None of them are exotic. All of them are expensive if they go unnoticed for more than a quarter.
1. Mixing personal and business expenses
The single most common issue we see in owner-run SMEs. It muddies your real margins, complicates tax filing, and is one of the first things an auditor flags. Keep a dedicated business account and card from day one.
2. Reconciling "when there's time"
Bank reconciliation done monthly catches errors while they're still cheap to fix. Done quarterly or "when things slow down," it turns into an archaeology project — and errors compound the longer they sit.
3. Treating cash flow and profit as the same thing
A profitable month on paper can still leave you unable to make payroll if receivables are slow. Track cash flow separately from your P&L, especially if you invoice on payment terms.
4. No paper trail for small transactions
Petty cash, small reimbursements and one-off purchases are exactly the entries that go missing supporting documentation. They're small individually, but they add up to a real gap when an auditor asks for evidence.
5. Misclassifying expenses
Filing a capital purchase as an operating expense (or vice versa) distorts your financials and can misstate your tax position. A consistent chart of accounts, reviewed periodically, prevents this from drifting over time.
6. Letting one person hold every key
When a single employee can raise a payment, approve it and reconcile it, you have no internal control at all. Even a two-person business benefits from separating who authorises a payment from who executes it.
7. Outgrowing spreadsheets without noticing
A spreadsheet that worked fine at 50 transactions a month becomes a liability at 500 — formulas break silently, version control disappears, and nobody notices until month-end doesn't add up. Cloud accounting software with automated bank feeds removes this failure mode entirely.
The fix is mostly about cadence
Almost none of these require sophisticated tools to solve — they require a consistent monthly process and someone accountable for running it. That's exactly what our bookkeeping team builds for clients: a monthly close that happens the same way, every month, with AI-assisted reconciliation catching what a rushed manual review would miss.
