The short answer
The most common accounting mistakes are mixing personal and business money, missing deadlines, poor record keeping, paying dividends without profits, forgetting to set aside tax, ignoring the director’s loan account, claiming the wrong expenses, filing the wrong VAT figures and not using an accountant early enough. Most are easy to avoid with simple habits.
Checked 26 October 2026. Rates for 2026/27.Key facts
| Fact | Detail |
|---|---|
| Most costly mistake | Missing deadlines |
| Most common | Mixing personal and business money |
| Dividends need | Retained profit |
| Tax savings pot | 20% to 25% of profit |
| Fix | Weekly bookkeeping and an annual calendar |
Mistake 1: mixing personal and business money
Using the company bank account for personal purchases, or paying business costs from a personal account, is the most common mistake. It makes bookkeeping confusing, risks an overdrawn director’s loan account, and can lead to tax charges. HMRC also treats the company and the director as separate persons, so personal spending is not a business cost.
The fix is simple. Keep a separate account for all company transactions, and pay yourself using salary, dividends or documented expense repayments. If you pay for a business cost personally, record it as a loan to the company, and reimburse yourself properly.
Mistake 2: missing deadlines
Filing deadlines catch many directors out. Accounts at Companies House, the CT600 and Corporation Tax payment, the confirmation statement, VAT returns and Self Assessment all have their own dates, and each has penalties. A missed accounts deadline brings an automatic penalty of £150 to £1,500, and a late Corporation Tax return starts at £100.
Create one calendar with every date for the year, and set reminders well ahead. A fixed-fee accountant who tracks your deadlines does the diarising for you, which makes lateness far less likely.
Mistake 3: poor record keeping
Missing receipts, unlabelled bank entries and scattered invoices make accounts slow and costly to prepare. They also mean that expenses may be disallowed for lack of evidence, so the company pays more tax than it should.
Capture records as you go. Use accounting software, photograph receipts straight away, and categorise transactions weekly. A tidy set of books saves time, fees and tax.
Mistake 4: paying dividends without profit
A dividend can only be paid from retained profit. Paying one when the company has insufficient reserves is unlawful, and the amount may be treated as a director’s loan that the company can reclaim, with tax consequences. Directors often declare dividends based on the bank balance, not the profit.
Check the retained profit before every dividend, using up-to-date management accounts. Keep board minutes and dividend vouchers, and ask your accountant if you are unsure.
Mistake 5: not setting aside money for tax
Corporation Tax, VAT, PAYE and personal tax on dividends all fall due at different times, and they can be large. Directors who spend the money in the bank find themselves unable to pay when the bill arrives, and then pay interest and penalties.
A good habit is to move a percentage of income into a tax savings account as it arrives. A rule of thumb is 20% to 25% of profit for Corporation Tax, the full VAT you collect, and 10% to 12% of dividends for personal tax.
Mistake 6: ignoring the director’s loan account
The director’s loan account can quietly become overdrawn through small personal payments. At year end, an overdrawn balance can trigger a charge of 35.75% of the amount if not cleared within nine months and one day, and benefit-in-kind tax if it exceeds £10,000.
Check the balance monthly. If it is overdrawn, plan how to clear it, through dividends, salary or repayment, before the deadline.
Mistakes 7 and 8: wrong expenses and VAT errors
Claiming personal costs as business expenses, or missing legitimate ones, both cost money. Personal items are disallowed and may need to be reclassified, while missing a valid expense means paying too much tax. Learn the wholly and exclusively rule and apply it consistently.
VAT errors are also common. Directors reclaim VAT on blocked items such as client entertainment, apply the wrong rate, or file returns with figures that do not match their records. Review each return before filing, and let your software or accountant apply the correct treatment.
Mistakes 9 and 10: leaving advice too late and ignoring planning
Many directors only contact an accountant after a deadline has passed or a problem has arisen. By then, options are limited. Getting advice during the year, ideally before major decisions, allows the accountant to suggest savings and prevent errors.
Finally, directors who ignore planning pay more tax than necessary. A pension contribution, a well-timed purchase, the right salary and dividend mix and a review before year end can all reduce the bill legitimately.
Building habits that prevent mistakes
A few simple habits prevent most of these mistakes. Keep a separate bank account. Do bookkeeping weekly. Keep an annual calendar of deadlines. Set aside tax as you earn. Review the director’s loan account monthly. And talk to your accountant at least once before the year end.
None of these takes much time, but together they keep the company compliant and reduce stress, and they leave you free to focus on the work you started the company to do.
What to do if you have already made a mistake
Do not panic. Most mistakes can be corrected if you act promptly. Tell your accountant, who can review the records, correct entries and, if needed, amend returns. If a filing was late, file as soon as possible, because penalties usually rise over time. If you paid a dividend without profits, take advice on treating it as a loan and repaying it. If VAT was claimed wrongly, correct it on the next return or tell HMRC. Disclosing errors voluntarily generally leads to lower penalties than waiting to be found out, so early action nearly always saves money.
How an annual review can prevent problems
A yearly health check with your accountant catches issues before they grow. Review the calendar of deadlines, the director’s loan account, the bookkeeping quality, the pay mix, the tax reserve and any upcoming changes in your business. Make decisions about pensions, equipment and dividends before the year end. A one-hour review each year costs little compared with the penalties, tax and stress it can avoid, and it gives you confidence that the company is in good order.
A short monthly checklist
To keep out of trouble, run through a short checklist each month. Reconcile the bank accounts and attach receipts. Check the director’s loan balance and clear any small overdrawn amount. Update your tax savings pot. Review upcoming deadlines for the next 60 days. Confirm that any dividends planned are covered by retained profit. Note any unusual transactions for your accountant. The whole routine takes less than an hour, and it prevents most of the mistakes described above from taking hold.
The bottom line
The most common accounting mistakes are mixing personal and business money, missing deadlines, poor record keeping, paying dividends without profits, forgetting to set aside tax, ignoring the director’s loan account, claiming the wrong expenses, filing the wrong VAT figures and not using an accountant early enough. If you would rather not do it alone, our fixed fees start at £45.83 + VAT a month.
Frequently asked questions
What is the most common mistake directors make?
Mixing personal and business money, which causes errors in the director’s loan account, bookkeeping and tax.
How much tax should I set aside?
A common guide is 20% to 25% of profit for Corporation Tax, all VAT collected, and about 10% to 12% of dividends for personal tax. Your accountant can refine this.
What happens if I pay a dividend I cannot afford?
The dividend may be unlawful, and the company can reclaim it from the shareholder. It can also be treated as a director’s loan, creating extra tax.
Can an accountant fix my mistakes?
Yes, in most cases, by correcting records, amending returns and negotiating with HMRC. The earlier you act, the cheaper it is to fix.
How can I avoid missing deadlines?
Keep a full calendar of dates, set reminders well in advance, and consider an accountant who tracks all your filing and payment deadlines for you.
How often should I review my accounts with an accountant?
At least once a year before your year end, and ideally quarterly if the business is growing or complex.
This article is general information, not personal tax or financial advice. Rules and rates change, so check GOV.UK or speak to an accountant about your circumstances. Rates shown are for 2026/27, last checked November 2026.