When Does Self Assessment Tax Have to Be Paid?
Navigate UK Self Assessment tax payment obligations and key deadlines to ensure timely compliance and manage your finances effectively.
Self Assessment tax is the system used in the UK to collect Income Tax from individuals who earn income not taxed at source, such as self-employed individuals, those with rental income, or those receiving certain types of investment income. This system ensures all taxable income is accounted for, allowing HM Revenue and Customs (HMRC) to calculate the correct amount of tax owed.
Key Annual Deadlines
The UK tax year runs from April 6th to April 5th of the following year. For individuals required to file a Self Assessment tax return, deadlines exist for both submission and payment. The primary deadline for submitting your online Self Assessment tax return is January 31st following the end of the tax year. For example, for the tax year ending April 5, 2025, the online submission deadline is January 31, 2026.
The main payment deadline for any tax owed, including Income Tax and any Class 2 and Class 4 National Insurance contributions, is also January 31st. Individuals who prefer to file a paper tax return have an earlier deadline of October 31st following the end of the tax year. For instance, for the tax year ending April 5, 2025, the paper return must be received by HMRC by October 31, 2025.
Payments on Account
Payments on Account are advance payments made towards your next year’s tax bill, designed to spread the cost of tax throughout the year. These payments are required if your last Self Assessment tax bill was over £1,000 and less than 80% of your tax was deducted at source, such as through a Pay As You Earn (PAYE) scheme.
These advance payments are calculated as 50% of your previous year’s tax bill. The first Payment on Account is due by January 31st, coinciding with the deadline for the previous year’s tax return and payment. The second Payment on Account is due six months later, by July 31st. For example, if your tax bill for the 2024/25 tax year was £3,000, your Payments on Account for the 2025/26 tax year would each be £1,500.
If you anticipate that your tax liability for the current year will be lower than the previous year, you can apply to reduce your Payments on Account. This can be done online through your HMRC account or by post using form SA303. If you reduce your payments too much and your actual tax bill ends up being higher, interest may be charged on the underpaid amount from the original due dates.
The Balancing Payment
The Balancing Payment is the final amount of tax due to settle your tax bill for the previous tax year. The deadline for this payment is also January 31st following the end of the tax year.
For instance, if your actual tax bill for the 2024/25 tax year was £3,500, but your Payments on Account totalled £3,000, you would need to make a Balancing Payment of £500 by January 31, 2026. This payment also includes any Capital Gains Tax or student loan repayments, which are not covered by Payments on Account. If your Payments on Account exceeded your actual tax liability, you would be due a refund rather than needing to make a Balancing Payment.
How to Pay Your Self Assessment Tax
HMRC offers several methods for paying your Self Assessment tax. One approach is through online or telephone banking using Faster Payments, CHAPS, or Bacs. When making a bank transfer, use the correct 11-character payment reference, which is your 10-digit Unique Taxpayer Reference (UTR) followed by the letter ‘K’. Payments via Faster Payments clear on the same or next day, while Bacs payments can take up to three working days.
Another option is to pay online using a debit card or a corporate credit card. Personal credit cards are not accepted for tax payments. You can also set up a Direct Debit with HMRC, which allows for regular payments towards your tax bill. The HMRC app also facilitates payments directly through your bank’s app or online banking.
Consequences of Missing Payment Deadlines
Missing Self Assessment payment deadlines can result in penalties and interest charges from HMRC. An initial automatic penalty of 5% of the tax unpaid is applied if the payment is 30 days late. Further 5% penalties can be charged if the tax remains unpaid after 6 months and again after 12 months. These penalties are in addition to any late filing penalties that may apply if the tax return was also submitted late.
Interest accrues on overdue tax from the day after the payment deadline. This interest is charged at HMRC’s published rate, which is above the Bank of England base rate. In cases of significant delays or non-payment, HMRC has the authority to pursue unpaid tax through debt collection procedures and, if necessary, legal action. While there is a concept of a “reasonable excuse” for late payment, HMRC applies this strictly, and it relates to unexpected events outside of your control.