Pay Self Assessment Through Your Tax Code (File by 30 December)
If you are a sole trader who also has a job or a pension, HMRC can collect your Self Assessment balance through your PAYE tax code instead of in one payment in January. It only works if you meet all three conditions, and it doesn't cover everything you might owe.
Written and reviewed by James Whitfield · Last reviewed 3 November 2026 · Checked against 2026/27 HMRC rates · Editorial standards · Methodology
You can pay your 2025/26 Self Assessment bill through your tax code if you owe less than £3,000, you already pay tax through PAYE, and you file online by 11:59pm on 30 December 2026 (paper returns by 31 October 2026).12 HMRC does it automatically unless you asked it not to on your return, and takes the amount from your salary or pension in equal instalments over 12 months.1 It covers the balancing payment: you cannot part-pay to get under £3,000, and Class 2 National Insurance cannot be collected this way.13
- →Online deadline: 30 December 2026. Miss it and you pay another way by 31 January 2027.2
- →Owe less than £3,000; making a part payment to get under it doesn't work.1
- →Not possible if you don't have enough PAYE income, would pay more than 50% of your PAYE income in tax, or would pay more than twice your normal tax.1
- →HMRC's manual: it is the balancing payment of £2,999.99 or less that is coded out.3
- →Payments on account, if you have them, are still paid by 31 January and 31 July.34
Related: Employed and self-employed tax calculator · Side hustle tax guide · Payments on account
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The three conditions
GOV.UK says HMRC will collect what you owe through your tax code if all of these apply: you owe less than £3,000 on your tax bill; you already pay tax through PAYE, for example as an employee or with a company pension; and you sent a paper return by 31 October or an online return by 30 December.1 For the 2025/26 return, those dates are 31 October 2026 and 30 December 2026.2
HMRC's Self Assessment Manual explains why the date matters: returns processed before the annual coding run in early January are considered automatically, and an online return sent after 30 December must not be coded out.3
When it won't work
You cannot pay through your tax code if you do not have enough PAYE income for HMRC to collect it, you would pay more than 50% of your PAYE income in tax, or you would end up paying more than twice as much tax as you normally do. If you owed £3,000 or more, paying some of it off to get under the limit does not make you eligible.1
If you are self-employed you cannot pay Class 2 National Insurance through your tax code (unless it has been due since before 6 April 2015).1 Most sole traders no longer pay Class 2, but if you chose to pay it voluntarily, pay that part by 31 January 2027 another way.
If you don't want it collected through your code, say so on your return: HMRC collects automatically unless you have asked it not to.1
Worked example: a small side business
Jo earns a £30,000 salary and made £4,000 profit from a weekend photography business in 2025/26. The salary uses the Personal Allowance, so the profit is taxed at 20%: £800.00 of Income Tax. There is no Class 4 because the profit is below £12,570, so the bill is £800.00.
| 2025/26 Self Assessment bill | £800.00 |
| Under £3,000, Jo pays PAYE, files online by 30 December 2026 | Can be coded out |
| Collected through Jo's tax code: 12 equal instalments of | £66.67 |
| Payments on account (bill under £1,000) | None |
Worked example: bigger profit, payments on account still due
Sam also earns £30,000 from a job but made £14,000 profit in 2025/26, the first year of trading. The bill is £2,800.00 Income Tax plus £85.80 Class 4: £2,885.80, under £3,000.
| 2025/26 balancing payment (nothing paid on account yet) | £2,885.80 |
| Coded out: collected through the tax code over 12 months | £2,885.80 |
| PAYE tax on the salary (£3,486.00) is under 80% of the total, so payments on account apply | |
| First payment on account for 2026/27, paid directly by 31 January 2027 | £1,442.90 |
| Second payment on account, paid directly by 31 July 2027 | £1,442.90 |
Should you choose it?
Spreading a bill over 12 months is easier on cash flow than one January payment, and the condition that you file by 30 December means your return is done a month early. The money is still yours to set aside: it just leaves through your payslip instead of a bank transfer. If you would rather pay in one go, or want to clear it before January, say on your return that you don't want it collected through your code.1
Frequently asked questions
What is the deadline to pay Self Assessment through my tax code?+
For the 2025/26 return, file online by 11:59pm on 30 December 2026, or on paper by 31 October 2026. If you file later, you pay the bill by 31 January 2027 another way.
Can I pay more than £3,000 through my tax code?+
Not for a Self Assessment balancing payment. You must owe less than £3,000, and paying part of a bigger bill to get under £3,000 doesn't make you eligible.
Are payments on account collected through my tax code?+
HMRC's manual describes coding out the balancing payment. If you have payments on account, plan to pay them directly by 31 January and 31 July.
How is the tax collected?+
In equal instalments over 12 months from your salary or pension, along with your usual tax.
Can Class 2 National Insurance be paid through my tax code?+
No, unless it has been due since before 6 April 2015. Pay voluntary Class 2 by 31 January another way.
Do I have to apply?+
No. HMRC collects it automatically if you meet all three conditions, unless you said on your return that you don't want it to.
Sources & references
The rates, thresholds and rules in this guide are drawn from the official HMRC and GOV.UK sources below, using the confirmed 2026/27 figures. Each link opens the relevant official page in a new tab.
- Pay your Self Assessment tax bill: through your tax code www.gov.uk/pay-self-assessment-tax-bill/through-your-tax-code
- Self Assessment tax returns: deadlines www.gov.uk/self-assessment-tax-returns/deadlines
- HMRC Self Assessment Manual SAM141001: transfer from SA to PAYE www.gov.uk/hmrc-internal-manuals/self-assessment-manual/sam141001
- Understand your Self Assessment tax bill: payments on account www.gov.uk/understand-self-assessment-bill/payments-on-account
Estimate your sole trader tax
The sole trader tax calculator turns this guidance into a concrete monthly take-home and tax reserve estimate, based on 2026/27 HMRC rates. Enter taxable profit — not turnover.