Form 64-8 is a tax form used by individuals in the United Kingdom to authorize a third party, such as an employer or a bank, to access their tax information online through the HM Revenue and Customs (HMRC) online services.

Form 64-8 allows a third party to view information about the taxpayer's tax affairs, such as their tax code, tax payments, and any tax credits or benefits that they are entitled to receive. It is typically used by employers to check the tax code of an employee and to ensure that the correct amount of tax is being withheld from their pay.

To complete Form 64-8, the taxpayer must provide their personal details, including their name, address, and National Insurance number, and the details of the third party that they are authorizing to access their tax information. The form must then be signed and returned to HMRC.

If you are a UK taxpayer and need to authorize a third party to access your tax information online, you will need to complete and submit Form 64-8. You can obtain the form from HMRC or from the third party that is requesting access to your information. It is important to carefully read and follow the instructions provided with the form to ensure that it is completed correctly.