Apply for a certificate of residence or letter of confirmation.
Sole traders, companies, and other organisations can now use an online HMRC service to apply for a certificate of residence or a letter of confirmation. These documents are used to claim tax relief under double taxation agreements or to provide proof of UK tax residence to foreign authorities. Applicants must provide details of the relevant tax period and the specific income involved, and cannot request a certificate for a future date.
Source: https://www.gov.uk/guidance/apply-for-a-certificate-of-residence-or-letter-of-confirmation. Summarised automatically from the official source — general information, not advice.