As far as trade with the UK (country code GB) is concerned, the submitting of Intrastat declarations will continue only until 31 December 2020. Read more about the annual changes in 2021 .
Regarding Intrastat declarations Suomi.fi identification and authorizations has been introduced in Customs´ Intrastat declaration service and in Posti Messaging´s Tyvi-service.
More information: Suomi.fi: instructions and support/general-instructions (DVV)