Have you checked your emails? HMRC would have emailed your user ID to you upon registration.
No luck? You can no longer recover your user ID online; you will therefore need to contact HMRC on 0300 200 3600. Please make sure you have your national insurance number or Self-Assessment UTR to hand!
Forgot your password?
You can reset your password on HMRC’s website. To do this, you will need:
Unique Taxpayer Reference
National Insurance number or postcode linked with the account
From 6th April 2020, if you’re UK resident and sell a residential property in the UK, you’ll have 30 days to report any gains to HMRC and pay any Capital Gains Tax due.