Self-Assessment Payment Timing Reform: How HMRC's Consultation Could Change Your Cash Flow

HMRC is consulting on a change that could reshape when self-employed people and sole traders actually hand over their tax — and it's worth understanding now, well before any changes take effect.

What's being proposed

According to HMRC's own figures, around one in five Income Tax Self Assessment bills are paid late. As part of the government's July 2026 "simplification, modernisation and fairness" package, a consultation is examining bringing payment timing forward, so tax is paid closer to when the income is actually earned, rather than the current system where a large chunk of tax on income earned in one year isn't settled until many months later.

Currently, Self Assessment tax for a tax year ending 5 April is due the following 31 January, with many taxpayers also making payments on account toward the next year's bill in January and July. That gap between earning income and paying tax on it is exactly what the consultation is targeting.

Why it matters for your cash flow

If payment timing moves closer to when income is earned, the upside is a smaller, more predictable final bill and less risk of a painful lump sum landing months after the money's been spent. The downside is less time to build up the cash to pay it — self-employed people currently benefit from an extended window to save, invest, or use that money in their business before tax is due. Any reform is likely to be phased in gradually rather than applied overnight, given the scale of behavioural and cash flow change involved for millions of self-employed taxpayers.

What to do now

• Don't wait for the reform to change your habits. Whatever the final design, saving toward your tax bill throughout the year — rather than at the deadline — protects you either way.
• Keep an eye on the consultation response. Reforms of this kind typically publish a formal response and draft timeline before anything becomes law.
• Review your payments on account. If your income has dropped, you can apply to reduce your payments on account rather than overpaying and waiting for a refund.
• Talk to your accountant about scenario planning if a large share of your income arrives in a concentrated period (e.g. seasonal businesses), since moving payment timing earlier could affect you more than someone with steady monthly income.

International comparison

The UK's current system, where tax lags income by up to 22 months in the worst case, is actually more generous timing-wise than some peers. In the US, self-employed people generally must make quarterly estimated tax payments throughout the year they earn the income, with penalties for underpayment even before the annual return is filed — a "pay as you earn" model close to what HMRC's consultation is edging toward. Australia's tax office similarly requires quarterly Pay As You Go (PAYG) instalments from many self-employed taxpayers, spreading the liability across the year rather than settling it long after the fact.

Key Numbers

• 1 in 5 — Self Assessment bills currently paid late, per HMRC
• 31 January — the current main annual payment deadline
• Quarterly — the payment frequency the US already requires of the self-employed, for comparison

Sources

• Tax update 2026: simplification, modernisation and fairness — GOV.UK
• Understand your Self Assessment tax bill: Payments on account — GOV.UK
• Self Assessment tax returns: deadlines — GOV.UK
• Estimated taxes — IRS.gov

Educational content only — not financial advice.