What TSS submits, and where it goes
TSS isn't a single system, it's a submission layer. Depending on the movement, it can generate:
- Entry summary declarations (safety & security data)
- Customs declarations for the goods themselves
- Internal Market Movement Information (for UKIMS-authorised traders)
- Simplified declaration processes, including Entry in Declarant's Records (EIDR)
- Supplementary declarations following a simplified movement
- Full declarations where no simplified route applies
- Transit movements ## The data model
Five data groups make up most declarations: party details (EORI, importer, exporter, declarant), goods detail (commodity code, description, quantity, weight, value, origin), customs treatment (procedure, value, duty position, preference/relief, authorisations), transport detail (mode, carrier, vehicle, route), and safety & security detail (consignor, consignee, routing).
Goods descriptions need to be specific enough for customs to identify the consignment. "Clothes" fails; "Men's cotton knitted shirts, size XL" passes. Vague descriptions are one of the most common causes of queries.
Registration prerequisites
Before touching the portal, you need an EORI number (issued by HMRC, not TSS), company registration details, and a designated user for declarations. Set up separate logins per user rather than sharing credentials, it keeps the audit trail intact.
Where TSS sits in the stack
TSS feeds four downstream systems: CDS for customs declarations, ICS2 for safety & security, GVMS for roll-on roll-off Goods Movement References, and NCTS for transit. You interact with TSS once; it routes to whichever of the four the movement needs.
Full breakdown here: Trader Support Service registration guide
