HMRC, Portals, Signing and more HM Revenue & CustomsLogin using Government Gateway Sign ItLogin to Docusign for an alternative signing solution SIC CodesStandard industrial classification of economic activities (SIC) Client PortalClient portal for logging into their accountancy manager portal The NLB WikiThe brain, wiki and knowledge centre HM Revenue & Customs EXC RatesExchange rates from HMRC in CSV and XML format