Where can I find my UTR number?
Once HMRC issue you a UTR, it stays with you forever. If you can't find it anywhere, you can see it on your HMRC personal tax account.
You can access your personal tax account here. This applies if you already have an account or if you need to sign up for one.
When you login, it should look something like the page below. Your UTR number would be where the black box is in the picture:
If you still can’t access your personal tax account, we suggest contacting HMRC through any of these channels here as we are not privy to this information.