I'm not sure if this has been shared before, but getting yourself an account set up on the CMS Gov.uk portal saves a lot of aggro.
https://www.gov.uk/child-maintenance-service/sign-in-account
Changes in personal circumstances, payments status' or income changes etc can all be done there.
https://www.gov.uk/child-maintenance-service/sign-in-account
Changes in personal circumstances, payments status' or income changes etc can all be done there.