Payments on Account: HMRC's Advance Tax Demand

1. The Core Mechanic

A Payment on Account is an advance instalment toward your next year's Income Tax and Class 4 National Insurance liability. The mechanic is blunt: HMRC assumes next year's tax bill will be identical to this year's, divides that bill in two, and collects each half six months apart.

The first instalment is due 31 January, the same day as your balancing payment for the year that just ended. The second is due 31 July. At the following 31 January, the two instalments are reconciled against the actual liability, any shortfall is collected as a balancing payment, and the cycle restarts with the first Payment on Account for the following year.

Capital Gains Tax, Student Loan repayments, and Class 2 NIC are explicitly excluded from the Payments on Account calculation. Only Income Tax and Class 4 NIC count, a subtlety that trips up first-time property disposers who expect their CGT to spread over two instalments.

2. Who Must Pay

Payments on Account are triggered automatically if your last Self Assessment liability exceeded £1,000 and less than 80% of your tax was collected at source through PAYE. Both tests must be failed for the regime to apply.

That second test matters for directors and high earners with significant PAYE income. If you file Self Assessment to report dividends or benefits-in-kind but the bulk of your tax has already been collected through payroll, you usually escape Payments on Account entirely, even if the Self Assessment balancing payment itself is several thousand pounds.

3. The First-Year Double Hit

Your first Self Assessment as a sole trader or landlord typically lands the hardest. At the first 31 January deadline you pay three things simultaneously: the balancing payment for the year just ended, plus the first 50% Payment on Account for the new year. The cashflow hit is effectively 150% of a normal year's tax.

Newly self-employed taxpayers routinely budget for the balancing payment only, arrive at the January deadline with the correct amount set aside, and discover their tax bill is 50% larger than expected. HMRC does not warn filers that Payments on Account are coming, they simply appear on the tax calculation.

4. Worked Example

A sole trader earns £60,000 profit in 2025/26. Their tax bill is approximately £14,400 (Income Tax plus Class 4 NIC, ignoring reliefs for clarity).

• 31 January 2027: £14,400 balancing payment + £7,200 first Payment on Account = £21,600.
• 31 July 2027: £7,200 second Payment on Account.
• 31 January 2028: actual 2026/27 liability reconciled. If the liability was £15,000, the balancing payment is £600 plus the first £7,500 Payment on Account for 2027/28, so £8,100 total.

The first year therefore costs £21,600 in January against a £14,400 true liability. Once the cycle is established, subsequent years settle into a more predictable rhythm, but the first January is the cash-flow inflection point for a filer who has not set aside the additional 50%, because the liability is effectively front-loaded by eighteen months relative to the income that produced it.

5. Reducing a Payment on Account

If you reasonably expect next year's liability to be lower, perhaps due to a known drop in trading, a change of business, retirement, or a large one-off item in the prior year, you can submit a formal claim to reduce your Payments on Account. This is done either within the Self Assessment return itself or via form SA303.

The claim is not rubber-stamped. If the actual liability turns out to be higher than your reduced estimate, HMRC charges interest on the shortfall from the original due date. Reducing Payments on Account aggressively to improve cashflow can therefore backfire, the interest rate is the Bank of England base rate plus 4%, currently around 7.75%.

Reductions should only be claimed with credible evidence. A pending contract loss, a maternity leave period, or a planned cessation of trade are legitimate. A general feeling that next year "won't be as good" is not, and the interest charge can turn a cashflow-management decision into a more expensive version of simply paying on time.

6. Interest, Penalties, and Time-to-Pay

Payments on Account attract interest from the original due date if not paid on time, at base rate + 4%. After 30 days, a 5% late payment penalty is added to any outstanding balancing payment (though not to the Payments on Account themselves). Further 5% penalties apply at six months and twelve months.

HMRC's Time-to-Pay arrangement allows filers to spread a Self Assessment liability over up to 12 months by direct debit, provided the debt is under £30,000 and the return is filed. Interest still accrues during the arrangement, but no late-payment penalties are added as long as the schedule is honoured. Time-to-Pay must be set up before the 31 January deadline to avoid penalties.

7. Cashflow Planning

The only reliable approach to Payments on Account is to treat tax money as already spent the moment it is earned. For most sole traders, provisioning 25-30% of every invoice into a separate holding account means January and July arrive with the liability already funded.

With MTD for ITSA landing in April 2026, the quarterly updates produce a running tax estimate inside your HMRC personal tax account, for the first time, Self Assessment filers can see their liability evolve in near-real time. Combining quarterly visibility with a disciplined tax provision account is the single biggest improvement most sole traders and landlords can make to their finances.

See our sole trader accounting service for full Self Assessment preparation and tax provisioning support.