It might depend on why its needed as to whether the cert needs specific information but e.g. a Family Home Declaration stating your marital status could be drawn up by your solicitor.
Tax cert showing you are single doesn't proove anything. Revenue Commissioners only know that you are married if you tell them. Thousands of people never contact Revenue after they get married as they don't feel they have to. 1) Because they are both high earning individuals and it will make no difference to them, 2) Because they don't know they are suppose to.