Essential information on your tax return
1. Government Gateway ID (also called user ID)
This is the ID you use to access the UK Government's secure online services. It usually has 12 digits.
Where can I find my Government Gateway ID? Try searching your emails, as your user ID may be included in an email sent to you by HMRC (or even the DVLA).
What if I can't find my ID or remember my password? If you can’t remember these details, follow the guidance from HMRC here.
First time doing your own tax return? Check your HMRC online account. You should see a box called 'Self Assessment'. If not, follow the instructions at the top of the page to 'Add a tax to your account'.
2. Unique Taxpayer Reference Number (UTR)
You get a 10-digit UTR number when you register for Self Assessment.
Where can I find my UTR number? You can see it in letters from HMRC about Self Assessment, your HMRC online account.
3. National Insurance number
You have a National Insurance number to ensure your National Insurance contributions and tax are correctly recorded. It is 9 digits long, with a mixture of letters and numbers.
Where can I find my National Insurance number? This is in many places, for example, payslips or Government letters about tax, pensions and benefits. You can also see it online in your HMRC online account.