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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 Self Assessment 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

You can file your Self Assessment tax return online.

If you need a paper form you can:

Deadlines

You must tell HMRC by 5 October if you need to complete a tax return for the previous year and you have either:

  • not sent a tax return before
  • registered before but did not need to send a tax return for the tax year 2023 to 2024

You could be fined if you do not tell HMRC by 5 October.

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

Send your tax return by the deadline.

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 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 and do not pay it through PAYE
  • you are an off-payroll worker who is repaying a student or postgraduate loan

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 for the previous year and you have either:

  • not sent a tax return before
  • registered before but did not need to send a tax return for the tax year 2023 to 2024

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 for Self Assessment

You must tell HMRC by 5 October if you need to complete a tax return for the previous year and you have either:

  • not sent a tax return before
  • registered before but did not need to send a tax return for the tax year 2023 to 2024

Check how to register for Self Assessment to find out how to tell HMRC. You may need to reactivate your Self Assessment account.

Your tax return may be delayed if you file it without reactivating an existing account.

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

Preparing for your tax bill 

You’ll need to pay your tax bill by 31 January. 

To prepare, once you’ve registered you can: 

4. Sending a return

You can send a tax return by either: 

  • submitting an online return  
  • sending a paper return 

You can get help filling in your return. 

When to send your tax return 

Check the filing deadlines. The deadline for sending a paper return is before the deadline for an online return. 

You can send your return any time after 5 April. Sending it earlier means you: 

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. 

Submit an online return  

You can file your Self Assessment tax return online.

Send a paper return 

If you need a paper copy of the main Self Assessment tax return you can: 

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. 

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

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.

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

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

HMRC needs time to review your request before the Self Assessment deadline of 31 January.

You may have to pay a penalty if you do not tell them early enough.

When you no longer need to send a tax return

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.

How to tell HMRC

Sign in to your account and fill in an online form to:

  • close your Self Assessment account
  • ask to be removed from Self Assessment for a specific tax year

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

If you cannot fill in the online form you can also contact HMRC by phone or post.

There’s a different way to tell HMRC if you want to stop paying the High Income Child Benefit Charge through Self Assessment and start paying the charge through PAYE.

If you’re no longer self-employed

You also need to tell HMRC that you’ve stopped being self-employed.

If you’ve already told HMRC that your self-employment has ended, HMRC may still ask you to send tax returns for future years.

If you’ve checked and you do not need to send a tax return, you’ll need to tell HMRC.

What happens next

You can view the progress of your form in your HMRC online account.

HMRC will write to you and confirm if you need to send a return.

6. Deadlines

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

If you do not know your profit for the whole tax year, you still need to send a tax return. Check how to send a return if you do not know your profit for the whole year.

The last tax year started on 6 April 2024 and ended on 5 April 2025. The deadline for earlier tax returns has passed and you may have to pay a penalty. Send your tax return or payment as soon as possible to avoid further penalties.

Telling HMRC you need to complete a return  

You must tell HMRC by 5 October if you need to complete a tax return for the previous year and you have either:

  • not sent a tax return before
  • registered before but did not need to send a tax return for the tax year 2023 to 2024

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

If you register after 5 October 2025 

HMRC will send you a letter or email with a different deadline to send your tax return by - this will be 3 months from the date on the letter or email. 

You must still pay the tax you owe by 11:59pm on 31 January 2026 or you’ll get a penalty.

Sending a paper tax return  

HMRC must receive your paper tax return by 11:59pm on 31 October 2025 or you’ll get a late filing penalty.    

You can send it any time on or after 6 April 2025 as long as HMRC receives it by the deadline. 

Submitting an online tax return  

You must submit your online tax return by 11:59pm on 31 January 2026 or you’ll get a late filing penalty.     

If you want to pay your Self Assessment bill through your tax code, you must submit it by 11:59pm on 30 December 2025. If you miss this deadline, you’ll have to pay another way.  

You can submit your return any time on or after 6 April 2025 up to the deadline. 

Paying the tax you owe  

You need to pay your Self Assessment tax by 11:59pm on 31 January 2026 or you’ll get a penalty.  

There is a second payment deadline of 31 July if you make payments towards your bill - these are known as ‘payments on account’.   

You can estimate your Self Assessment tax bill before sending your tax return to:   

  • give you an idea of what your bill is likely to be 
  • allow you to budget and pay on time 

 Find help on understanding the tax you owe. 

Trustees of a registered pension scheme or non-resident companies 

HMRC must receive a paper tax return by 31 January 2026. You cannot send a return online. 

You can send it any time on or after 6 April 2025 as long as HMRC receives it by the deadline. 

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 

7. Penalties

You’ll get a penalty if you need to complete a tax return and you: 

  • send your return late 
  • pay your tax bill late 

You can estimate your penalty for late Self Assessment tax returns and payments. 

If you register for Self Assessment late 

If you register after 5 October and do not pay all of your tax bill by 31 January, you may get a ‘failure to notify’ penalty.  

This penalty is based on the amount still left to pay and you’ll receive it within 12 months after HMRC receives your Self Assessment tax return. 

You can find more information on ‘failure to notify’ penalties.

If you send your tax return late 

You’ll get the following late filing penalties: 

  • an initial £100 penalty 
  • after 3 months, additional daily penalties of £10 per day, up to a maximum of £900 
  • after 6 months, a further penalty of 5% of the tax due or £300, whichever is greater 
  • after 12 months, another 5% or £300 charge, whichever is greater 

To avoid this, send your Self Assessment tax return as soon as possible. 

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

If you pay your tax late 

You’ll get penalties of 5% of the tax unpaid at: 

  • 30 days 
  • 6 months 
  • 12 months 

You’ll also be charged interest on the amount owed. To avoid this, pay your Self Assessment tax bill as soon as possible. 

Find out what happens if you do not pay your tax bill.

Paying a penalty 

You must pay within 30 days of the date on the penalty notice. Find out how to pay a penalty.

If you disagree with a penalty 

If you have a reasonable excuse, you can appeal against a penalty.

8. 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.

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 2023 to 2024 tax year, you’ll usually need to change your return by 31 January 2026.

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 to your account.

  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 you can:

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.

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 to your account and choose ‘View statements’ from the left-hand menu.

If you’re owed tax

You may be able to claim a tax refund.

If you need to pay more tax

Your updated bill will also show:

If you sent an updated paper return

HMRC will send you an updated bill. 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.

If you’ve missed the deadline to change your return

If your return is incorrect and it’s more than 12 months after the Self Assessment deadline you’ll need to write to HMRC to:

  • report income you did not include in your tax return
  • claim overpayment relief, if you think you’ve overpaid tax

Reporting income you did not include in your tax return

You should contact HMRC in writing and include:

  • the tax year you’re correcting
  • why you think you’ve paid too little tax
  • how much you think you’ve underpaid
  • your signature

HMRC will review your information, and contact you if they need more details. The amount you owe may be updated based on what you tell them.

Claiming overpayment relief

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

You should contact HMRC in writing, you must include:

  • that you’re making a claim for overpayment relief
  • the tax year for which you think you paid too much tax
  • why you think you’ve paid too much tax
  • how much you think you’ve overpaid
  • if you have, or have not, previously made an appeal for the same payment

If you do not include all of this information your claim will be rejected.

You must include a declaration saying the details you have given are ‘correct and complete to the best of your information and belief’. The declaration must be signed by:

  • you, if you are claiming for yourself
  • a company officer (for example a director, shadow director, company secretary or manager of the company) if the claim is for a limited company

No one else, including a tax agent, can sign on your behalf.

You can also tell HMRC how you want to be repaid in your letter.

HMRC will review your information, and contact you if they need more details. The amount you owe may be updated based on what you tell them.

You need to keep evidence of the tax you think has been overpaid for the relevant period as HMRC may ask for this later.

9. Claiming a tax refund

You may be able to get a tax refund (also known as a ‘repayment’ or ‘rebate’) if you’ve paid too much tax. You can check how to claim a tax refund.

You may not get a refund if you have tax due in the next 45 days (for example for a payment on account). Instead, the money will be deducted from the tax you owe.

If you’ve already claimed a tax refund

You can check when you can expect a reply from HMRC about your claim.

The status of your refund may show as ‘pending’ in your online tax account. This means that the refund has been created but still needs to be approved and paid.

10. How to get help

Find out what support is available to help you fill in your tax return and understand more about Self Assessment. You can also find out what to do if you need extra support.

Help filling in your Self Assessment tax return

There is help text throughout the online tax return that gives information on completing each section.

You can also find guidance to help you understand and fill in the sections of your Self Assessment tax return.

For example, there are sections on:

  • self-employment 
  • employment 
  • pensions 
  • other UK income 
  • property 
  • capital gains

If you complete a paper tax return, there are guidance notes you can download to help you.

Understanding Self Assessment

You can use HMRC email updates, videos and webinars for Self Assessment to find more guidance on Self Assessment, such as:

  • if you’re filling in your Self Assessment tax return for the first time
  • understanding your Self Assessment statement
  • how to budget for your Self Assessment tax bill
  • using the HMRC app to make a payment
  • setting up a Time to Pay arrangement

You can also use HMRC’s digital assistant to ask questions about Self Assessment.

If you need extra support

If your health condition or personal circumstances make it difficult when you contact HMRC, you can:

If you need to contact HMRC

You can get:

11. 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.