What payment of Self Assessment tax covers
Your Self Assessment statement can include Income Tax, Class 4 National Insurance, Capital Gains Tax, student loan repayments and other amounts calculated through your return. HMRC shows the total due and allocates payments against your Self Assessment account.
For the return covering 6 April 2025 to 5 April 2026, HMRC’s online filing and balancing-payment deadline is 31 January 2027. This payment settles what remains after tax deducted at source and any earlier payments on account.
If you are setting money aside from self-employment income, use SupportFund’s household budget planner to separate the tax reserve from essential living costs.
Check the tax year before paying. HMRC may show several liabilities on the same account, including a balancing payment for 2025/26 and the first payment on account for 2026/27, both due on 31 January 2027.
Self Assessment payment deadlines for 2026/27
The amount due in January can contain two separate charges. HMRC requires the previous tax year’s balancing payment and, where applicable, the first advance payment towards the current tax year on the same date.
| HMRC deadline | What may be due | Tax year affected |
|---|---|---|
| 31 January 2027 | Balancing payment | 2025/26 |
| 31 January 2027 | First payment on account | 2026/27 |
| 31 July 2027 | Second payment on account | 2026/27 |
| 31 January 2028 | Any balancing payment still due | 2026/27 |
These dates follow HMRC’s official Self Assessment payment timetable. HMRC also sets 31 October 2026 as the deadline for a paper 2025/26 return and 31 January 2027 for an online return.
Submitting early does not bring forward the statutory payment deadline, but it reveals the bill sooner. That can leave more time to challenge an error, adjust a payment on account or seek confidential debt help before enforcement action begins.
When HMRC requires payments on account
According to HMRC, payments on account normally apply when your previous Self Assessment tax bill was more than £1,000, unless more than 80% of the relevant tax was collected outside Self Assessment, such as through PAYE. The test is not triggered by a bill of exactly £1,000.
Each payment on account is normally half of the previous year’s qualifying tax bill, according to HMRC. Qualifying tax generally includes Income Tax and Class 4 National Insurance but excludes Capital Gains Tax and student loan repayments.
Example of the calculation
If HMRC calculates a qualifying 2025/26 bill of £2,400, each 2026/27 payment on account would ordinarily be £1,200. This is an illustration of HMRC’s half-and-half calculation rather than an estimate of any reader’s liability.
If the eventual 2026/27 liability is higher, the difference is normally payable by 31 January 2028; if it is lower, HMRC adjusts the account. Review your HMRC calculation rather than assuming the January total is a duplicate charge.
Reducing payments on account safely
HMRC allows you to claim a reduction if you reasonably expect the current year’s qualifying tax liability to be lower. This may be appropriate after reduced profits, stopping self-employment, losing taxable rental income or having more tax collected through PAYE.
You can apply through your HMRC online account or submit form SA303. Base the reduction on current records and a realistic forecast rather than the amount you can currently afford.
Warning: HMRC charges interest if you reduce payments on account too far and the final liability shows that more should have been paid. A reduction changes the forecast liability; it is not a payment holiday or debt-relief arrangement.
Keep invoices, accounts, payslips and evidence supporting the forecast. If unpredictable income is affecting household essentials, explore grants and local support separately rather than understating taxable profit.
How to pay and what to do if money is short
HMRC accepts Self Assessment payments through approved methods including online or telephone banking, debit card, Direct Debit and bank transfer. Use the correct payment reference—normally your 10-digit Unique Taxpayer Reference followed by the letter K, as specified by HMRC—so the money reaches the right account.
Processing times differ by method, so check HMRC’s current payment guidance before the deadline. Do not rely on an instruction date if HMRC states that the payment must have cleared into its account.
If you cannot pay in full
- File the return on time. Filing and payment are separate obligations under HMRC rules.
- Pay what you can. This reduces the balance on which HMRC may charge late-payment interest.
- Check HMRC’s online payment-plan service. Eligibility depends on your circumstances and the status of the debt.
- Contact HMRC promptly. Ask about a Time to Pay arrangement if the online route is unavailable or unsuitable.
HMRC charges late-payment interest at a variable official rate, so confirm the rate applying on the day you pay. HMRC also states that late-payment penalties can arise at 30 days, 6 months and 12 months, generally calculated as 5% of the unpaid tax at each stage, subject to its statutory rules and any agreed Time to Pay protection.
Practical tip: Never ignore HMRC correspondence because you cannot clear the full balance. An agreed arrangement is different from simply making occasional payments without HMRC’s approval.
Rates and rules can change: confirm current amounts, interest rates, deadlines and payment-plan conditions on GOV.UK before acting.