Payment on Account UK: Why Your January Tax Bill Is Bigger

Payment on account is one of the most common sources of financial shock for newly self-employed people in the UK. You complete your first Self Assessment return, expect to pay one bill — then HMRC asks for almost double. This guide explains exactly how payment on account works, who it applies to, and what you can do to prepare.

What is payment on account?

Payment on account is HMRC's system for collecting Self Assessment tax in advance. Rather than waiting until 31 January to collect all of your tax for the previous year, HMRC also requires advance payments toward the following year's bill.

The logic is timing. Without payment on account, a sole trader who started earning in April 2025 would not pay tax on that income until January 2027 — nearly 22 months later. HMRC closes that gap by requiring two advance instalments spread through the year.

Who has to make payments on account in the UK?

Payments on account apply when both of the following conditions are met:

• Your Self Assessment tax bill for the year is more than £1,000, AND
• Less than 80% of your tax was collected at source (for example, through PAYE on a day job)

If you are primarily employed and have only a small amount of freelance income, you may fall below the threshold. But the majority of sole traders with a meaningful self-employed income will meet both conditions and will be required to make payments on account.

Note that payments on account only cover Income Tax and Class 4 National Insurance. They do not apply to Capital Gains Tax or student loan repayments — those are settled in full through your annual balancing payment.

How payment on account is calculated

Each payment on account is 50% of your previous tax year's total Self Assessment bill — Income Tax and Class 4 National Insurance combined. You make two payments, each half of last year's bill.

Here is a practical example using a £4,000 tax bill for 2024–25:

Payment	Due date	Amount
Balancing payment for 2024–25	31 January 2026	£4,000
First payment on account for 2025–26	31 January 2026	£2,000
Second payment on account for 2025–26	31 July 2026	£2,000
Balancing payment for 2025–26 (if bill differs)	31 January 2027	Variable

If your actual tax for 2025–26 turns out to be £4,800, you pay the £800 shortfall as a balancing payment in January 2027. If your actual bill is £3,200, you receive an £800 refund or credit against the following year.

The first-year shock: why your January payment on account bill is bigger than you think

The cash flow impact hits hardest in the first year your tax bill exceeds £1,000. Here is what happens:

You have spent the year earning and setting aside what you thought was enough to cover your bill. In January, HMRC asks for two things at once:

1. Your full tax bill for the year just ended
2. The first payment on account — 50% of that same bill — toward the current year

The result: your January payment is 150% of your annual tax liability. A £3,000 tax bill becomes a £4,500 payment. A £6,000 bill becomes a £9,000 January payment.

This is not a penalty. HMRC is not punishing you. It is the advance collection system doing exactly what it is designed to do. But it catches thousands of sole traders off guard every January simply because nobody told them it was coming.

Can you reduce your payment on account?

Yes — if your income is genuinely falling. You can apply to reduce your payments on account through your HMRC online account or when filing your Self Assessment return. HMRC will ask you to estimate your expected income for the year and calculate revised payments accordingly.

Legitimate reasons to apply for a reduction include:

• Losing a significant client and income genuinely falling in the current year
• Taking extended leave (maternity, paternity, or illness) that substantially reduces your earnings
• Moving into employment and winding down self-employment

If you are unsure whether a reduction is appropriate in your situation, an accountant can advise based on your actual numbers.

How to prepare: building a tax buffer throughout the year

The most reliable way to handle payment on account is to save more than you think you need — consistently, from the moment income arrives.

A practical rule of thumb: set aside 25–30% of every client payment into a dedicated tax savings account. Do this the day the money arrives, before it can be spent on anything else. Keeping it separate from your current account removes the temptation to dip into it.

In your first full year of self-employment, aim for the higher end of that range — 28–30%. The extra buffer covers the payment on account that will land on top of your regular tax bill in January.

If you also claim allowable expenses as a sole trader, your actual tax bill will be lower than your gross income suggests — which is another reason to track expenses carefully throughout the year rather than reconstructing them in January.

How accounting software helps track your UK payment on account position

Good accounting software monitors your income and expenses in real time and produces a running estimate of your total Self Assessment liability — including payments on account. This takes the guesswork out of January.

FreeAgent includes a dedicated tax timeline dashboard that displays your current estimated tax bill alongside your January and July payment dates. Xero and QuickBooks offer similar tax liability summaries through their dashboards and reporting tools. All three are HMRC-recognised for Making Tax Digital submissions.

This real-time visibility becomes increasingly important with Making Tax Digital for Income Tax approaching. From April 2026, sole traders earning over £50,000 will be required to submit quarterly income and expense updates to HMRC. Check whether MTD applies to you if you are not yet sure of your position.

If you are in the early stages of self-employment, the first priority is making sure you have registered for Self Assessment with HMRC — payment on account only becomes relevant once your first return is filed and your first bill assessed.

The short version: payment on account is not optional, it is not a penalty, and it is not going away. Plan for it from day one and it becomes a manageable part of your annual tax rhythm rather than a January crisis.