After 31 years working with small businesses across Brighton and Hove, the bookkeeping problems I see are almost always the same ones. They are not complicated mistakes — they are simple habits that quietly cost money, cause stress at year end, and occasionally lead to penalties. Here is what they are and how to fix them.
Mistake 1: Mixing personal and business finances
This is the most common and the most damaging. Using your personal bank account for business transactions, or paying for personal expenses from the business account, creates a mess that takes hours to untangle at year end — and creates genuine risk if HMRC ever scrutinises your records.
The fix: Open a separate business bank account and use it exclusively for business. Pay yourself a regular transfer to your personal account and treat it as your salary. Keep everything else separate.
Mistake 2: Keeping records in a shoebox (or nowhere at all)
Receipts on the back seat of the van. Invoices in an email folder no one has sorted. Bank statements downloaded and never looked at. By the time your accountant asks for the year's records, it is a half-day reconstruction job that should have taken minutes.
The fix: Use cloud accounting software. Xero and QuickBooks connect directly to your bank account and import transactions automatically. Take a photo of paper receipts on the spot with the mobile app. The record-keeping happens as you go rather than in one horrifying session in January.
Mistake 3: Forgetting to record cash transactions
Tradespeople are particularly vulnerable to this. Cash jobs paid on site, materials bought at the builders' merchant with cash, fuel paid out of pocket. These all need to be in your records — both as income and as allowable expenses.
The fix: Record every cash transaction the same day it happens. A simple note in your phone, transferred to your accounting software that evening. Nothing complicated — just consistent.
Mistake 4: Claiming expenses you are not entitled to
This goes both ways. Some business owners claim obviously personal expenses as business costs — client lunches that were really family dinners, holidays that were vaguely described as business trips. This is a tax fraud risk. On the other side, many business owners miss legitimate expenses they are fully entitled to claim — home office costs, professional subscriptions, business mileage, equipment purchases. Both problems cost you money.
The fix: Understand the rule: an expense is allowable if it is incurred wholly and exclusively for business purposes. If in doubt, ask your accountant — not the internet.
Mistake 5: Not reconciling your bank account
Bank reconciliation means checking that every transaction in your accounting software matches your bank statement. Without it, errors accumulate silently — duplicate transactions, missed payments, incorrect amounts. By the time they surface, they can be difficult to trace.
The fix: Reconcile monthly. Cloud accounting software makes this straightforward — it imports your bank feed automatically and flags anything that doesn't match. It takes 15 minutes if you do it regularly.
Mistake 6: Ignoring VAT until it becomes a crisis
Businesses approaching the £90,000 VAT registration threshold sometimes fail to notice until they have already exceeded it — meaning they owe HMRC VAT on past sales they never collected. Others register but file returns late or miscalculate the amounts due. VAT penalties are automatic and can be significant.
The fix: Monitor your rolling 12-month turnover regularly. Know your threshold. Set calendar reminders for VAT return deadlines. If you are unsure whether you need to register, call us — it takes five minutes to confirm.
Mistake 7: Leaving everything until January
The self-assessment filing deadline is 31 January. Every year, a significant proportion of Brighton business owners start gathering their records in late December. The result is stress, rushed work, missing information, and almost certainly a higher accountancy bill than necessary.
The fix: File early. There is no reason to wait until January. If your tax year ended 5 April, your records are complete by May. File in the summer and you know your tax bill six months early — giving you time to plan for the payment.
Mistake 8: Not keeping records for long enough
HMRC can enquire into your tax returns for up to four years after the filing date in a standard enquiry, and up to six years if they believe there has been an error. You need to retain records for at least six years — longer if you have property transactions or losses being carried forward.
The fix: Cloud accounting software stores everything automatically. For paper records, a simple filing system with annual folders is sufficient — just keep them for the required period before disposal.