Self-assessment Self-assessment online

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Most people now make their tax return online. 

Making an online tax return is straightforward but you need to register in good time and plan ahead to meet the self-assessment deadline on 31 January. 

Registering an online tax return

If you are filing online for the first time, follow these key steps to submit a successful tax return:

  • Check you are eligible to make a self-assessment tax return. HMRC should have written to you in April. If in doubt, call the self-assessment Helpline on 0845 900 0444 or write to HM Revenue & Customs, Self Assessment, PO Box 4000, Cardiff, CF14 8HR.
  • Know your ten-digit 'Unique Taxpayer Reference'. HMRC should have issued this, which is referred to as UTR. If you don't know it, contact the telephone helpline and they will send it by post to your home address. They can't tell you it over the phone. You will also need your National Insurance number.
  • Register to use HMRC Online services. Log on to the registration page of its website and select 'Self Assessment'.
  • Set up an online account. You need to create a password and receive a User ID. The User ID will be sent to you online. Make sure you keep a note of this as you will need it to log on. If you forget the User ID, you can get HMRC to send it again by email or post. They can also issue a replacement password if you forget this.
  • Receive an activation code by post. This is similar to the security code issued by credit card providers. It takes about a week to arrive, so make sure you leave enough time.
  • Log on and activate your account. Make sure you do this within 28 days of receipt, or the code will expire and you'll have to request another one.

Filing an online tax return is very similar to completing a paper return. The main difference is that supplementary pages are added as you go, rather than having to be ordered in advance. Online notes appear as you complete each question rather than in a separate guide.

Before you start to enter figures, make sure you have all the information you need. Most commonly this includes:

  • employment details on form P60 or P45
  • pension contributions or receipts
  • income from letting property or land
  • capital gains or losses
  • income from UK savings & investments
  • life insurance gains and AVC refunds
  • any other taxable income
  • gifts to charity if you're claiming tax relief

Making an online tax return

If you don’t have exact figures, you can submit an estimate or a provisional figure. Explain how you arrived at your totals in the 'additional information' section and why you can't use actual figures. Estimated figures are acceptable if waiting for final ones would make you miss the self-assessment deadline.

Save your online return as you go - you don’t need to complete it all in one session. If you have difficulty, there is an HMRC Online services telephone helpline (0845 60 55 99). Once you are ready to submit a return re-enter your user ID and password. You can print off your return to keep a hard copy. HMRC will immediately acknowledge receipt of your online tax return.   

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