Preparing for the Customs Declaration Service Find out what you need to do to prepare for making declarations on the Customs Declaration Service. From: Contents You need to: Consider getting someone to do declarations for you, such as a Customs Agent, freight forwarder or fast parcel operator. You can also use the Trader Support Service to help with the new processes under the Northern Ireland Protocol. Have a Government Gateway user ID, and get access to the Customs Declaration Service. If you do not already have a Government Gateway user ID you can get it at the same time. Make sure you have an Economic Operator Registration and Identification (EORI) number. If you’re getting an EORI for the first time, you can get access to the Customs Declaration Service at the same time.