The short answer
Payments on account are advance payments towards a future Self Assessment bill. For many sole traders, landlords, directors and side-income earners, the 31 January payment is not just the tax still owed for the return that has been filed. It can also include the first advance payment for the current tax year.
The second advance payment is normally due by 31 July. That means Self Assessment planning should not stop when the return is filed. The useful question is: how much cash should be set aside across the year so the next January does not become a scramble?
Why the bill catches people out
- The person budgets for one tax bill, then sees a balancing payment plus a payment on account.
- Income has risen, but the tax set-aside routine has not changed.
- Side income, rental income or dividends were not separated from day-to-day spending.
- Current-year income has dropped, but the HMRC account still reflects the previous year.
- Receipts and expenses are left until January, so the likely bill is unclear for too long.
When reducing payments needs care
If current-year income is genuinely lower, it may be possible to ask HMRC to reduce payments on account. That should not be treated as a cashflow shortcut. If the reduction is too aggressive, the later catch-up bill can be painful and interest may apply.
A safer review compares the previous tax calculation with realistic current-year income, allowable costs, PAYE deductions, pension contributions, dividends, property income and any one-off changes. The aim is not to guess low. It is to avoid both overpaying unnecessarily and underpaying because the records were incomplete.
Records to gather before a review
- The latest Self Assessment calculation and HMRC statement of account.
- Current-year income estimates by source: trade, property, dividends, employment, pension or side income.
- Business bank statements, sales reports, platform payouts or invoices.
- Receipts and evidence for costs being claimed.
- Notes on major changes: stopped trading, new employment, lower profits, property sale, large equipment purchase or a new company structure.
A practical set-aside routine
For small businesses, the best fix is usually boring: update records monthly, estimate tax before the deadline season, and keep tax money separate from working cash. A simple quarterly check gives enough time to spot whether January and July are likely to be comfortable, tight or genuinely wrong.
That routine also improves the Self Assessment return itself. Cleaner records make it easier to check expenses, spot missing income, plan pension or dividend questions, and avoid treating tax as a once-a-year emergency.
How Gardian can help
A focused Self Assessment review can check the return position, the payment-on-account pattern, the evidence behind claims and the next deadline. If the issue is really bookkeeping, company/director planning or property records, the review can route the owner to the right support before the next deadline pressure starts.