HMRC CIS is an online service provided by HM Revenue and Customs (HMRC) in the United Kingdom for contractors who are registered for the Construction Industry Scheme (CIS). The CIS is a tax deduction scheme that applies to contractors and subcontractors in the construction industry.

To log in to HMRC CIS, you will need to have a Government Gateway account. If you do not already have an account, you will need to create one by following the steps on the HMRC website. Once you have an account, you can log in to HMRC CIS by visiting the HMRC website and entering your user ID and password.

If you are a contractor or subcontractor in the UK construction industry and are registered for the CIS, it is important to keep your HMRC CIS login details secure and to update them if they change. You can use HMRC CIS to view your tax deductions and other tax information and to report any changes to your circumstances. If you have any questions or need help with HMRC CIS, you can contact HMRC for assistance.