Self Assessment tax returns

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1. Overview

Self Assessment is a system HM Revenue and Customs (HMRC) uses to collect Income Tax.

Tax is usually deducted automatically from wages and pensions. People and businesses with other income must report it in a tax return.

If you need to send a Self Assessment tax return, fill it in after the end of the tax year (5 April) it applies to.

You must send a return if HMRC asks you to.

You may have to pay interest and a penalty if you do not file and pay on time.

This guide is also available in Welsh (Cymraeg).

Sending your return

File your tax return online or call HMRC and request form SA100.

Deadlines

Send your tax return by the deadline.

You must tell HMRC by 5 October if you need to complete a tax return and you have not sent one before. You could be fined if you do not.

You can tell HMRC by registering for Self Assessment. Check how to register for Self Assessment.

Filling in your return

You need to keep records (for example bank statements or receipts) so you can fill in your tax return correctly.

You can get help filling in your return.

Paying your bill

HMRC will calculate what you owe based on what you report.

Pay your Self Assessment bill by 31 January.

How much tax you pay will depend on the Income Tax band you’re in. There’s a different rate for Capital Gains Tax if you need to pay it, for example you sell shares or a second home.

2. Who must send a tax return

You must send a tax return if, in the last tax year (6 April to 5 April), any of the following applied:

  • you were self-employed as a ‘sole trader’ and earned more than £1,000 (before taking off anything you can claim tax relief on)
  • you were a partner in a business partnership
  • you had a total taxable income of more than £150,000
  • you had to pay Capital Gains Tax when you sold or ‘disposed of’ something that increased in value
  • you had to pay the High Income Child Benefit Charge

You may also need to send a tax return if you have any untaxed income, such as:

  • money from renting out a property
  • tips and commission
  • income from savings, investments and dividends
  • foreign income

Check if you need to send a tax return

You can check if you need to send a tax return if you’re not sure.

You must tell HMRC by 5 October if you need to complete a tax return and have not sent one before. You can tell HMRC by registering for Self Assessment.

Other reasons for sending a return

You can choose to fill in a tax return to:

3. Registering and sending a return

You must register for Self Assessment if you have to send a tax return and you have not sent one before.

Check how to register for Self Assessment.

If you’re new to Self Assessment, you’ll need to keep records (for example bank statements or receipts) so you can fill in your tax return correctly.

You can get help filling in your return.

Once you register, you must send your Self Assessment tax return to HMRC by the deadline.

Send a return online

You can file your Self Assessment tax return online.

The deadline for sending a return online is 31 January.

Send a paper return

If you need a paper copy of the main Self Assessment tax return, call HMRC and request form SA100.

If you need to send a tax return for trustees of a registered pension, you must download form SA970.

You can download all other forms and supplementary pages.

The deadline for sending a return using a paper form is 31 October (or 31 January if you’re a trustee of a registered pension scheme or a non-resident company).

The address to send the form to is:

Self Assessment
HM Revenue and Customs
BX9 1AS
United Kingdom

After sending your paper return, you can check when to expect a reply from HMRC.

If you’re sending an SA100 tax return for the 2021 to 2022 tax year or earlier, get forms from the National Archives.

Use commercial software to send a return

You can use commercial software:

  • for a partnership
  • for a trust and estate
  • if you get income from a trust
  • if you lived abroad as a non-resident
  • if you’re a Lloyd’s underwriter
  • if you’re a religious minister
  • to report profits made on selling or disposing of more than one asset (‘chargeable gains’)

Find a commercial software supplier.

4. If you no longer need to send a tax return

You must tell HMRC if you believe you no longer need to send a tax return.

If HMRC agrees, they’ll send a letter confirming you do not need to file a return.

You may have to pay a penalty if HMRC do not agree before the Self Assessment deadline of 31 January.

You might no longer need to send a return because, for example:

You can check if you need to send a tax return if you’re not sure.

You can tell HMRC:

You’ll need to provide your National Insurance number and your UTR number.

5. Deadlines

HM Revenue and Customs (HMRC) must receive your tax return and any money you owe by the deadline.

The last tax year started on 6 April 2023 and ended on 5 April 2024.

Deadline for telling HMRC you need to complete a return

You must tell HMRC by 5 October if you need to complete a tax return and have not sent one before.

You can tell HMRC by registering for Self Assessment.

Deadline for submitting a paper return

If you’re doing a paper tax return, you must submit it by midnight 31 October 2024.

Deadline for submitting an online return

If you’re doing an online tax return, you must submit it by midnight 31 January 2025.

Deadlines for paying tax you owe

You need to pay the tax you owe by midnight 31 January 2025.

There’s usually a second payment deadline of 31 July if you make advance payments towards your bill (known as ‘payments on account’).

You’ll usually pay a penalty if you’re late. You can appeal against a penalty if you have a reasonable excuse.

If you do not know your profit for the whole tax year

You might not know what your profit will be for the whole tax year if, for example:

  • your ‘accounting period’ ends at a different time to the end of the tax year
  • your ‘accounting period’ is different to your ‘basis period’
  • you’re waiting for a valuation

An ‘accounting period’ is the period which a business’s accounts are made up to (often 12 months) and gives the business year end. This can be different to the period used to identify the profits taxable in any particular tax year (also known as a ‘basis period’).

If you do not know what your profit will be for the whole tax year before the reporting deadline, you should work out what it’s likely to be (known as ‘provisional figures’) and include those.

You should tell HMRC that you’ve used provisional figures when you submit your return.

When you find out what your profit was for the whole tax year, you’ll need to  change your return. You have 12 months from the Self Assessment deadline to make these changes.

If more tax is due, you’ll need to pay interest on the difference between your estimates and the final figures. The interest will be worked out from the original due date for payment. If you have overpaid tax then you’ll get interest paid to you.

When the deadline is different

Submit your online return by 30 December if you want HMRC to automatically collect tax you owe from your wages and pension. Find out if you are eligible to pay this way.

HMRC must receive a paper tax return by 31 January if you’re a trustee of a registered pension scheme or a non-resident company. You cannot send a return online.

HMRC might also email or write to you giving you a different deadline if they were late in sending out your return.

Partnership returns if you have a company as a partner

If your partnership’s accounting date is between 1 February and 5 April and one of your partners is a limited company, the deadline for:

  • online returns is 12 months from the accounting date
  • paper returns is 9 months from the accounting date

2022 to 2023 tax year and earlier

The Self Assessment deadline for these tax years has passed. Send your tax return or payment as soon as possible - you’ll have to pay a penalty.

6. Penalties

You’ll get a penalty if you need to send a tax return and you miss the deadline for submitting it or paying your bill.

You’ll pay a late filing penalty of £100 if your tax return is up to 3 months late. You’ll have to pay more if it’s later, or if you pay your tax bill late.

You’ll be charged interest on late payments.

Estimate your penalty for Self Assessment tax returns more than 3 months late, and late payments.

You can appeal against a penalty if you have a reasonable excuse.

Find out how to pay a penalty.

All partners can be charged a penalty if a partnership tax return is late.

7. If you need to change your return

You can make a change to a tax return after you filed it, for example because you made a mistake.

Your bill will be updated based on what you report. You may have to pay more tax or be able to claim a refund.

There’s a different process if you need to report foreign income.

Updating your tax return

You can correct a tax return within 12 months of the Self Assessment deadline, online or by sending another paper return.

Example

For the 2022 to 2023 tax year, you’ll usually need to change your return by 31 January 2025.

If you miss the deadline or if you need to make a change to a return from an earlier tax year you’ll need to write to HMRC.

Online tax returns

You must wait 3 days (72 hours) after filing before updating your return.

  1. Sign in using your Government Gateway user ID and password.

  2. From ‘Your tax account’, choose ’Self Assessment account’.

  3. Choose ‘More Self Assessment details’.

  4. Choose ‘At a glance’ from the left-hand menu.

  5. Choose ‘Tax return options’.

  6. Choose the tax year for the return you want to amend.

  7. Go into the tax return, make the corrections and file it again.

Paper tax returns

For the main Self Assessment tax return, call HMRC and request form SA100. You can download all other forms and supplementary pages.

You then need to send the corrected pages to the address on your Self Assessment paperwork.

Write ‘amendment’ on each page and include your name and Unique Taxpayer Reference (UTR) - this is on previous tax returns or letters from HMRC.

If you cannot find the address, you can send your corrections to:

Self Assessment
HM Revenue and Customs
BX9 1AS

If you used commercial software

Contact the software provider for help correcting your tax return. Contact HMRC if your software is not able to make corrections.

Write to HMRC

You must contact HMRC in writing if you’ve missed the deadline to make changes or you need to make a change to another tax year.

You’ll also need to write HMRC a letter to:

  • claim overpayment relief
  • report income you did not include in your tax return

You can claim a refund up to 4 years after the end of the tax year it relates to.

What to include

You must include:

  • the tax year you’re correcting
  • why you think you’ve paid too much or little tax
  • how much you think you’ve over or underpaid
  • your signature (no one else can sign on your behalf)

If you’re making a claim, also include in your letter:

  • that you’re making a claim for overpayment relief
  • proof that you’d paid tax through Self Assessment for the relevant period
  • how you want to be repaid
  • that you have not previously tried to claim back this refund
  • a signed declaration saying that the details you’ve given are correct and complete to the best of your knowledge

Changes to your bill

You’ll see your amended bill straight away if you updated your tax return online. Within 3 days, your statement will also show:

  • the difference from the old one, so you can see whether you owe more or less tax
  • any interest

To view this, sign in using your Government Gateway user ID and password and choose ‘View statements’ from the left-hand menu.

If you’re owed tax

To claim a refund, go to ‘Request a repayment’ from the left-hand menu within your HMRC online account. Allow 4 weeks for your refund to be sent to your bank account.

You may not get a refund if you have tax due in the next 35 days (for example for a payment on account). Instead, the money will be deducted from the tax you owe.

If you need to pay more tax

Your updated bill will also show:

If you sent an updated paper return

HMRC will usually send you an updated bill within 4 weeks.

It’s taking longer than usual to process changes. You can check when you can expect a reply from HMRC.

They’ll pay any refund directly into your bank account, as long as you include your bank details on your tax return.

8. How to get help

If you need help with Self Assessment, you can:

Help filling in your return

There’s introductory guidance on GOV.UK to:

Guidance notes and helpsheets

You can also read guidance in:

9. Returns for someone who has died

If you’re the ‘personal representative’ (an executor or administrator) for someone who has died, you might need to complete:

  • a Self Assessment tax return for income the person earned before they died 
  • a separate Self Assessment tax return for income the ‘estate’ generated after the person died

A personal representative is legally responsible for dealing with the deceased’s money, property and possessions (their estate).

If you have not already told HMRC about a death you must do this as soon as possible. Use the Tell Us Once service to let HMRC and other government organisations know about the death.

Returns for income the person earned before they died

HMRC will tell you if you need to fill in a Self Assessment tax return for the person who has died. If you do, they’ll send you a form to complete and return.

You’ll usually need details of the deceased’s bank and savings accounts, for example:

  • bank statements

  • building society pass books

  • dividend vouchers

  • National Savings bonds or certificates

If the deceased was employed you’ll usually need:

  • a P45 from their employer - if the return is for the tax year they died 

  • a P60 from their employer - if the return is for a tax year before the tax year they died

  • details of any expenses paid by the employer - for example company cars, health insurance, travel expenses or childcare

If the deceased was receiving a pension you’ll usually need: 

  • a final statement from their pension provider - if the return is for the tax year they died

  • an end of year certificate from their pension provider - if the return is for a tax year before the tax year they died

  • confirmation of any state pension

You’ll also need details of any other income they had, for example if they rented out property or ran their own business.

Contact HMRC’s Bereavement helpline if you need help completing a return for someone who has died or if you cannot find their records.

Sending the return

Send the completed Self Assessment form by post. 

The return must reach HMRC by the date given in the letter you received with the form.

You can hire a professional (such as an accountant) to help you submit a tax return on behalf of the deceased.

Returns for income the estate generated after the person died

If the estate generates any new income after the death, you may also need to do both of the following:  

  • register with HMRC 

  • send a separate tax return on behalf of the estate

You must check if you need to tell HMRC about the estate’s income.