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If you're a higher rate tax payer, a company director or have more complicated tax affairs you may need to complete a tax return. You can send your return online or on paper. You have three months longer to send it if you send it online.
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If you send your return online, you can tailor it and just complete the pages you need. You get online help as you work through the form. Your tax is worked out automatically and you get an acknowledgement when HM Revenue & Customs (HMRC) receives your return. You have longer to send in the return than if you use a paper form. You have until 31 January following the end of the tax year instead of 31 October.
You need to register for HMRC Online Services if you want to send your return online.
You usually receive a letter in April or May each year telling you to complete your tax return. If you want to send your tax return on paper, you can download the forms or order them from HMRC.
Make sure that you put your ten-digit tax reference number, called your Unique Taxpayer Reference, on your tax return if you download it. You'll find this reference number on statements and letters from HMRC.
You use the main tax return form (SA100) to give basic details such as your name, address and straightforward investment income.
You may need some supplementary pages to tell HMRC about other income and gains, for example income from employment, income from property, or capital gains. Each supplementary page has a helpsheet to help you fill it in.
If you complete your tax return online instead, you don't need all these different forms. You just add the pages you need as you go.
You can only fill in the Short Tax Return if HMRC tells you that you can. They will do so by sending you the tax return form or form SA316D in April or May.
HMRC will only ask you to complete this form if your tax affairs are straightforward.
You may prefer to send your tax return online instead. It's straightforward and you can tailor your return online so that you only see the pages you need. You must register for HMRC Online Services first.
For the tax year (6 April to the following 5 April) you'll need records relating to:
You may also need records relating to:
You'll need to provide your bank details if you want any tax repaid directly to your account. HMRC recommends this as it is quick and secure.
If you don't have exact figures you can use:
If you use a provisional figure, you must tell HMRC when the actual figures will be available.
You should use the 'Additional Information' section to say how you arrived at the figures and why you can't use actual figures. If adjustments are made at a later date and you haven't paid enough tax you may have to pay interest and penalties.
If you send in a paper tax return, it must reach HMRC by midnight on 31 October. If you miss this deadline, you'll need to send your return online instead. If you don't, you'll have to pay a penalty.
You should send your return back in the envelope provided or send it to the Tax Office shown on the front page of the form. You won't get a receipt if you send a paper tax return.
If you've downloaded the form, it may not show a Tax Office address. You'll need to check your Self Assessment statement - or a letter from HMRC - to find the right address to send it to. Alternatively, you can follow the link below to find an address. Make sure that the form also shows your ten-digit taxpayer reference number before you send it.
If you send your return online, it must reach HMRC by midnight on 31 January. You'll get an acknowledgment that HMRC has received your return. If you send your tax return back late, you'll have to pay a penalty, so make sure you send it on time.
If you make a mistake, HMRC may need to contact you before they can accept your return. So if you're sending a paper tax return:
You can avoid many mistakes by sending your tax return online, but make sure you:
You'll need to register to use HMRC Online Services to send your tax return online, even if you use commercial software.
If you need help with filling in your tax return, you can ring the Self Assessment Helpline.
You'll receive a tax calculation if you completed a paper tax return and asked for one. For online tax returns, you see this earlier, before you send your return.
If you are due a repayment of tax, you'll usually get this automatically. But it may be set off against other tax instead if there is an amount due soon.
If you have tax to pay, it will either be collected through your tax code or you will have to pay it by 31 January. Check your Self Assessment statement to find out more.