This Saturday, 31 October 2026, is the paper Self Assessment deadline. The online deadline is 31 January 2027. Filing online gives you three more months to find out exactly what you owe.
We at Pivot Cloud are working through this countdown with our clients across Richmond and South West London right now. This guide sets out the dates, the payment trap that catches first time filers, who must file, and what to send us and when.
Your dates at a glance
The return covers the tax year from 6 April 2025 to 5 April 2026. These are the dates that matter for most people:
- Saturday 31 October 2026, 11:59pm. HMRC must receive a paper return by this time. Posting it on the day is not enough.
- Wednesday 30 December 2026, 11:59pm. File online by this time if you want a bill under £3,000 collected through your PAYE tax code, where that option applies to you.
- Sunday 31 January 2027, 11:59pm. Submit your online return by this time, and pay the tax you owe by this time.
- Saturday 31 July 2027. Pay your second payment on account by this date, if payments on account apply to you.
Keep two ideas separate. The paper deadline is about how you file. The payment deadline is about when you pay. Filing on paper does not bring your payment date forward.
If the Saturday deadline passes you by, switch to the online route and file by 31 January 2027.
If you have not registered yet, register now
The usual date to tell HMRC you need to send a return was 5 October 2026. It applied if you had not sent a return before, or did not need one for 2024 to 2025.
Missing 5 October does not end your filing season. Register now. HMRC will send you a letter or email with your own filing deadline, three months from that letter or email. Your payment deadline does not move. Tax is still due by 11:59pm on 31 January 2027.
You need a Unique Taxpayer Reference before you can file, and it comes by post, so do not leave registration until January.
Filing early does not mean paying early
This is the single most useful fact in the whole countdown. You can file your return in November and still pay on 31 January 2027. HMRC does not ask for the money on the day you file.
Filing early buys you three things: the exact bill, so you can budget for it; time to speak to HMRC about payment options if you cannot pay in full; and time to fix a figure that looks wrong.
Aim for a November or early December finish. January is for checking and paying.
Why the January bill can be larger than expected
For many people, the January payment has two parts, and the second part is the surprise.
The first part is the balancing payment: the tax still owed for 2025 to 2026 after any tax already paid. Capital Gains Tax and student loan repayments, where they apply to a self employed person, are also settled here rather than through payments on account.
The second part is the first payment on account for 2026 to 2027. Payments on account are advance payments towards your next tax bill, each usually half of the tax you owed last year. The first is due on 31 January 2027. The second is due on 31 July 2027.
An example: a £4,000 bill for 2025 to 2026, with no payments on account made, means £4,000 plus a £2,000 first payment on account on 31 January 2027, £6,000 in total, with a further £2,000 on 31 July 2027.
Payments on account do not apply to everyone. You do not make them if the tax you owed last year was less than £1,000, or if you paid more than 80 percent of last year’s tax outside Self Assessment, for example through your tax code.
If you expect lower income for 2026 to 2027, you can ask HMRC to reduce your payments on account, online or by sending form SA303. Use real figures. If you reduce them too far, HMRC charges interest on the difference.
Who must file a return
You must send a return if HMRC asks you to, or if, in the last tax year, any of the following applied: you were self employed as a sole trader and earned more than £1,000, before tax relief; you were a partner in a business partnership; you had to pay Capital Gains Tax on a disposal; you had to pay the High Income Child Benefit Charge and you do not pay it through PAYE; or you were an off-payroll worker repaying a student or postgraduate loan.
You may also need to send a return if you have untaxed income, such as rent, tips and commission, savings interest, dividends, foreign income, or taxable UK income if you are a non-UK resident. If you are not sure, use the GOV.UK checker or ask us.
Our legal considerations for self-employed professionals covers the basics behind a sole trader return, from registration to record keeping.
The Child Benefit cases that catch higher earners
Child Benefit brings a separate group into Self Assessment, often for the first time. The High Income Child Benefit Charge applies where you or your partner receive Child Benefit and the higher earner has adjusted net income over £60,000. Adjusted net income is total taxable income, including savings interest and dividends, before Personal Allowances and less reliefs such as pension contributions and Gift Aid.
The charge is 1 percent of the Child Benefit for every £200 over £60,000. At £80,000 you pay it all back. If both you and your partner are over the threshold, the higher earner pays the charge.
There is an important exception. If paying the charge is your only reason for sending a return, you may be able to pay it through PAYE instead, by having your tax code adjusted. That route is only open if you do not need a return for another reason, and it is on or before 31 January after that tax year. For 2025 to 2026, that means on or before 31 January 2027. After that date, or if you need a return for another reason, the charge must go through Self Assessment.
Opting out of payments is not cancelling the claim. You stay registered, you do not pay the charge, and you still build National Insurance credits towards your State Pension.
Our tax reliefs for parents guide explains the wider childcare picture. If the charge is your only filing reason, bring your adjusted net income figure to us.
What happens if you miss a deadline
The penalty ladder is fixed, and it applies even if no tax is due. A late return brings an initial £100 penalty, then after three months £10 per day up to £900, then after six months 5 percent of the tax due or £300, whichever is greater, and after twelve months the same again.
Late payment brings its own penalties: 5 percent of the tax unpaid at 30 days, at six months and at twelve months, plus interest. Filing on time but paying late is still a problem, but it is one problem instead of two. If you cannot pay in full, file on time and contact HMRC early.
If you have a reasonable excuse, you can appeal against a penalty. Keep the evidence. Being busy in January is not, in itself, a reasonable excuse.
Our client countdown: what to send us, and when
By mid-November: send us your records. For most clients this means your P60 or P45, business and rental records, bank interest certificates, dividend vouchers, pension statements, Gift Aid records, and Child Benefit details where they apply.
By early December: check the draft with us. We prepare the return, you check every income source and figure, and we agree the payment figure together.
By mid-January: pay on time. Set the payment aside so 31 January is a payment date, not a scramble.
Start the countdown now
The paper deadline this Saturday is the starting gun, not the finish line. Three months is enough time to file carefully and plan the payment. It is not enough time if the first step is taken in the last week of January.
We at Pivot Cloud prepare Self Assessment returns for sole traders, landlords, company directors, and higher earning parents across Richmond and South West London. If you would like us to take on your 2025 to 2026 return, or work out your balancing payment and payments on account before January, book a free initial consultation on 020 8287 1047 or through our contact page. You can also read about our Self Assessment service.
File early. Pay on time. Keep January calm.
Disclaimer
This guide provides general information about Self Assessment and the 31 January 2027 deadline as of October 2026. Tax rules and HMRC guidance can change. Always consult with a qualified tax professional about your specific circumstances. That’s what we’re here for. In accordance with our normal practice, this reference is given in good faith and in confidence, without legal liability on the part of the author or the company. The author assumes no responsibility or liability for any errors or omissions in the content of this site.
The information provided in this blog is for general guidance and educational purposes only and does not constitute financial, tax, accounting or legal advice. Pivot Cloud Ltd, registered in England and Wales under Company Registration Number 14570549, has prepared this content to offer general insights into financial and taxation matters. Although every effort is made to ensure the accuracy and relevance of the information at the time of publication, no guarantee is given regarding completeness, accuracy or suitability for your specific circumstances.
Readers should not act, or refrain from acting, based solely on the information contained in this content. Professional advice tailored to your personal or business situation should always be obtained before taking any financial or tax related decision. Pivot Cloud Ltd accepts no liability for any loss or damage arising from reliance on the information presented in this blog.