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Who needs to complete a Self Assessment tax return?

Not everyone needs to complete a tax return. If your tax affairs are straightforward you may already pay all of the tax due on your earnings or pensions through your PAYE (Pay As You Earn) tax code.

But you may need to complete a tax return if you have more complicated tax affairs, even if you already pay tax through PAYE. There are also certain circumstances in which you will always need to complete a tax return - for example if you're self-employed, a company director, a trustee or if you have foreign income.

• Find out more about who needs to complete a tax return

How to get a Self Assessment tax return

HMRC normally sends out your Self Assessment tax return in April each year - if you file online they send a letter called a 'Notice to File' instead. If you usually complete a tax return but it hasn't arrived by the end of April, you should get in touch with your Tax Office.

If you haven’t completed a tax return before (or it's been a while since you did), you'll need to complete a Self Assessment registration form before you can get a tax return. Please read the sections below to find out which form you need to complete. You'll need to have your National Insurance number to hand before you start.

• Find out how to get a National Insurance number

Self-employed

If you're in business you need to complete form CWF1 to register as self-employed and tell HMRC about your business. Follow the link below to do this online, over the phone or to download the form. When you register as self-employed, you'll be registered for Self Assessment at the same time.

• Register as self-employed Opens new window

If you're not self-employed

If you're not self-employed, you need to complete form SA1 to let HMRC know what has changed.

• Download form SA1 to register for Self Assessment (PDF, 31K) Opens new window

• Help with PDF files

What happens next?

HMRC will set up tax records for you and send you a Unique Taxpayer Reference (UTR). If any tax returns need completing straight away they'll send these to you too.

In April each year, you'll receive either a tax return or, if you decide to file online, a letter called a 'Notice to File'.

Tax return deadlines and penalties

If you send in a paper tax return, it must reach HMRC by midnight on 31 October.

If you send in your tax return online it must reach HMRC by midnight on 31 January.

You'll be charged a penalty if your tax return isn't received on time.

There are a few exceptions to the above dates, for example if you receive your tax return late or HMRC doesn't allow you to file online. Follow the link below to find out more.

• Find out more about tax return deadlines and penalties

Filing your tax return online

Filing your tax return online has many advantages - for example your figures are calculated automatically and you'll know right away what you owe or what is owed to you.

You need to register for HMRC Online Services before you can file online.

Once you've registered, you can use HMRC's free Self Assessment service or buy commercial software to file most tax returns online.

You must use commercial software to file certain tax return forms online, as the free HMRC service does not cover them, for example:

• Partnership Return
• Trust and Estate Tax Return
• Some pages that support the main tax return, eg those for Lloyd's members and ministers of religion

Tax returns you can't send online

You have to send the following returns on paper:

• SA700 - Non-resident Company Tax Return
• SA970 - Trustees of Registered Pension Schemes

There is currently no online service available for these tax returns, but the deadline is the same as for online returns - 31 January.

• File your tax return online - find out more