Online tax calculator

HMRC-recognised tax calculator

Calculate and submit your income tax bill online

Self-assessment tax calculator

We've teamed up with SimpleTax to bring you an online self-assessment tool allowing Which? members to calculate their tax bill and submit it directly to HMRC at no extra cost - £30 for non-members.

  • Easy to use and jargon-free personal tax calculator
  • Safe and secure - protected by 256-bit encryption
  • A simple and quick way to calculate your tax bill
  • Officially recognised by HMRC
  • Submit your tax return directly to HMRC as part of your Which? membership package - £30 for non-members

Already a Which? member?

If you're an existing Which? member, or have just signed up for a trial, you can now calculate your tax bill and submit to HMRC as part of your membership package.

Use the calculator now

If you're not a Which? member, you can still use the tool, but you'll need to pay a charge of £30 if you want to submit your completed tax return to HMRC.

Access the tool as a non Which? member

Do I need to complete a self-assessment tax return?

If HMRC has asked you to complete a self-assessment return for 2016-2017, you must complete it before 31 January 2018 or face a £100 fine. Some people (those who are self-employed, for example) need to complete a tax return every year; others are sent one because they have untaxed income (often from property). If your affairs are complex, you may want to consider receiving independent specialist advice in respect of your tax submission. On some occasions, HMRC may require a paper submission of your tax return - it’s your responsibility to find out if this is the case.


Use of the service is governed by the terms and conditions of SimpleTax. Although the publisher endeavours to make sure the information in this calculator is accurate and up-to-date, nothing in it constitutes taxation advice by Which? and should never be construed as such. You should consult a qualified tax adviser if taxation advice is required. Which? Limited does not accept any liability for any loss or damage suffered as a consequence of relying on any information contained in this guide. Which? will receive a referral fee for any user that pays the £30 fee to submit a tax return using the SimpleTax calculator. You can calculate and submit your tax return for free on the HMRC website. Limited information will be shared between Which? and SimpleTax in accordance with the respective privacy policies.

Old tax calculator

After the launch of the new calculator in November 2016, we continued to support the old version until 31 March 2017. This version has now been decommissioned and can no longer be accessed.

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