Self Assessment Deadlines for Sole Traders: Key Dates 2026/27

The self assessment deadlines for sole traders are covered in this post – everything you need to know for the 2026/27 tax year — in one place, in plain English.

Miss the Self Assessment deadline and HMRC issues an automatic £100 penalty — even if you have no tax to pay. No warning letter, no grace period. Just an automatic fine on 1 February.

The Key Dates at a Glance

Standard Self Assessment (income under £50,000):

Making Tax Digital (income over £50,000 from April 2026):

Each Deadline Explained

5 October 2026 — Register for Self Assessment

If you started self-employment during the 2025/26 tax year (6 April 2025 to 5 April 2026) and haven’t yet registered with HMRC, this is your deadline.

Registering tells HMRC you need to file a tax return. Once registered, HMRC issues your Unique Taxpayer Reference (UTR) — the 10-digit number you need to file. Allow up to 21 days for it to arrive by post.

Miss this deadline and HMRC will still accept a late registration — but you may face a penalty, and you’ll have less time to get your UTR and file before January.

Already registered from a previous year? You don’t need to register again — just file your return as normal.

Read => How to Register as Self-Employed in the UK

31 October 2026 — Paper Tax Return Deadline

If you’re filing a paper Self Assessment return for 2025/26, HMRC must receive it by 11:59pm on 31 October 2026.

Almost everyone files online — it’s faster, HMRC calculates your bill automatically, and you get three extra months. If you’re still filing on paper, it’s worth switching to online filing before the next tax year.

30 December 2026 — PAYE Code Collection Deadline

This one only applies if you’re both employed and self-employed.

If you owe less than £3,000 in Self Assessment tax and submit your online return by 30 December, HMRC may collect it through your PAYE tax code adjustment the following April — rather than requiring a separate payment by January. This spreads the cost but means you’ll pay it through your payslip over the following year.

If you’d rather pay in one go by January, ignore this deadline and just file by 31 January instead.

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31 January 2027 — The Big One

The online tax return for the 2025/26 tax year must be submitted by 11:59pm on 31 January 2027. This is also the date any tax owed must be paid.

Three things are due on this date:

1. Your Self Assessment tax return — the return covering your income and expenses from 6 April 2025 to 5 April 2026.

2. Your tax bill — Income Tax and Class 4 National Insurance on your 2025/26 profits.

3. Your first payment on account — if your tax bill exceeds £1,000, HMRC also requires an advance payment of 50% of your bill towards the following year. This catches a lot of first-year sole traders off guard — your January payment can be up to 150% of your annual tax bill.

Can you file early? Yes — you can submit your return any time on or after 6 April 2026 up to the deadline. Filing early doesn’t mean paying early — your bill is still due 31 January 2027 regardless of when you file. But filing early means you know your bill months in advance, which makes budgeting much easier.

31 July 2027 — Second Payment on Account

If your 2025/26 tax bill exceeded £1,000, your second payment on account is due on 31 July 2027 — another 50% of your previous year’s bill, as an advance towards 2026/27.

If you expect your income to be significantly lower in 2026/27, you can apply to reduce your payments on account through your HMRC online account. Only do this if you’re confident your income will be lower — if you reduce them too much and your income is higher, you’ll owe the difference plus interest.

What Happens If You Miss a Deadline

Missed the filing deadline (31 January):

You will have to pay a late filing penalty of £100 if your tax return is up to 3 months late. If you are over three months late, you will be charged a daily penalty of £10 per day, to a maximum of £900. After 6 months, a further penalty of 5% of the tax due or £300 (whichever is greater) may be applied.

These penalties apply even if you have no tax to pay.

Missed the payment deadline (31 January):

Interest accrues on unpaid tax from 1 February at the current HMRC rate. Additional penalties apply at 30 days, 6 months, and 12 months late — typically 5% of the outstanding amount at each point.

If you can’t pay: Contact HMRC as soon as possible and ask about a Time to Pay arrangement — monthly instalments to spread the cost. You need to have filed your return first. Call 0300 200 3822 or apply through your HMRC online account.

MTD Deadlines (Income Over £50,000)

If your gross self-employment income exceeds £50,000, Making Tax Digital applies to you from April 2026. Under MTD you no longer file one annual tax return — instead you submit four quarterly updates throughout the year, plus a Final Declaration by 31 January.

The four quarterly update deadlines for 2026/27:

Each quarterly update is a summary of your business income and expenses for that period — submitted directly through your MTD-compatible software.

The Final Declaration — due 31 January 2027 — is where you confirm your full-year figures, add any other income sources, and finalise your tax position. It replaces the traditional Self Assessment return.

Payment deadlines are unchanged — tax is still due 31 January and 31 July regardless of whether you’re on MTD or standard Self Assessment.

Soft landing for 2026/27: HMRC has confirmed no penalty points for late quarterly updates in the first year. This gives newly mandated sole traders time to get their systems right. The soft landing does not cover the Final Declaration or late payments — those penalties apply from day one.

Read => Making Tax Digital: What’s Changed and What You Need to Do

How to Make Sure You Never Miss a Deadline

1. Put every date in your calendar now Set reminders for 5 October, 31 January, and 31 July. Add them as recurring annual events so you never have to think about it again.

2. File early The filing window opens 6 April — file in April or May and you know your bill eight months before it’s due. No January panic, no last-minute scramble.

3. Set aside tax as you go 25–30% of every payment received, moved to a separate pot immediately. If you do this consistently, 31 January is never a crisis.

4. Use accounting software Good software keeps your records organised throughout the year, tracks your income and expenses automatically, and makes filing straightforward rather than stressful. The difference between a sole trader who dreads January and one who doesn’t is usually a system — not effort.

Members of The Self Employed Club get 90% off Xero for 6 months — MTD-compatible accounting software that keeps your records ready all year round. Grab the deal →

Read => Self Assessment Tax Return for Sole Traders: A Step-by-Step Guide
Read => Self-Employed Tax: How It Works and What You Need to Know

2026/27 Self Assessment Deadlines — Summary

Standard Self Assessment:

Making Tax Digital (income over £50,000):

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