Quarterly Tax Payments Could Reshape Cash Flow for UK Small Businesses

The biggest challenge in the planned UK tax payment changes may be timing. From the 2029-2030 tax year, millions of people who currently pay income tax through self-assessment are expected to pay during the year their income arises. That could make tax collection more regular, but it also means sole traders and other taxpayers will need to track earnings and set cash aside while their income is still coming in.

The proposed change covers around 12 million people. That includes self-employed workers, owners of small businesses run as sole traders, landlords and people with more complex tax affairs. Sole traders are in scope; owners who operate through limited companies are not described as part of this group in the announced plan.

From one annual return to payments during the year

Under the current timetable, self-assessment taxpayers file a tax return after the tax year ends. For the 2025-2026 tax year, which ends on 5 April 2026, the return deadline is 31 January 2027. Many taxpayers will already have paid part of their estimated bill before then: half is due by 31 January 2026, and the other half by 31 July 2026. Any remaining tax shown on the return is due by 31 January 2027, alongside an initial payment towards the 2026-2027 bill.

The planned system would bring payments into the tax year itself. Quarterly payments are considered likely, though monthly payments are also a possibility. The precise schedule and other final details have yet to be agreed, so taxpayers cannot yet plan around a confirmed set of payment dates.

The Treasury estimates the change will raise £1.3 billion in 2029-2030 and £1.8 billion two years later. It says that collecting tax closer to when income is earned would make some tax avoidance strategies harder. It also points to cases where small businesses close before paying tax they owe, leaving those bills uncollected.

Cash flow will need closer attention

For a business with steady income, regular tax payments may be easier to budget for than a large bill later. But self-employed earnings can vary across a year, and customers may take time to pay invoices. A quarterly payment date could arrive during a slow period, even if the business has earned more at another point in the year. That makes up-to-date records and a separate reserve for tax more useful: an invoice sent is not the same as cash received.

There is also a difference between submitting income information and paying a bill. Making Tax Digital has been extended to self-assessment income tax, requiring many taxpayers to make quarterly electronic submissions. Take-up has been slow, and the current requirement is to provide information rather than make payments. The proposed reform would add a payment responsibility to the existing reporting work, increasing the importance of keeping records current throughout the year.

Around two million affected taxpayers also have jobs covered by PAYE as well as income to report through self-assessment. HM Revenue & Customs expects to collect the tax owed by most of them through PAYE. The remaining ten million self-assessment taxpayers will need to arrange payment themselves. For people with both types of income, the collection method may therefore depend on their circumstances.

The first year could bring two bills together

The transition may create the sharpest pressure. In 2029-2030, many taxpayers could owe tax based on their earnings during that year while still having an unpaid liability from 2028-2029. Paying both within the same period could strain cash reserves, especially for businesses whose earnings fluctuate or whose customers pay late.

That makes the transition year a separate planning problem from the long-term routine. A taxpayer who can build a reserve before the change may find it easier to handle overlapping liabilities, but the amount and timing will depend on their own income and tax position. With the payment frequency and final arrangements still unsettled, detailed planning will need to wait for those terms.

Small-business groups and accountants have called for the changes to be delayed while details are finalized. The planned move is still set for 2029-2030; a delay, if one occurs, would shift the adjustment rather than remove the need to manage tax payments during the year. For now, the practical steps are to keep income records current, watch for confirmed payment rules and treat tax reserves as part of cash-flow planning.