If your load is leaving the UK, crossing the EU under seal and arriving at a customs office somewhere that is not the port it came into, there is a very good chance it moves under a T1 transit document. Here is what that actually means, in plain English.
What a T1 is for
A T1 is a customs document submitted under the Common Transit Convention (CTC). It lets non-Union goods travel between two customs offices — the office of departure and the office of destination — without paying duty and VAT at every internal border along the way. The duties and taxes are suspended, not waived; they are resolved (or not) at the office of destination.
In practice, UK hauliers use T1s for things like:
- UK goods going to an EU inland destination through more than one country.
- Non-Union goods that entered the UK under temporary storage and need to leave again under seal.
- Goods passing through Türkiye, Serbia, North Macedonia, Switzerland or other CTC signatories on their way to the EU.
What gets produced
When a T1 is lodged successfully on the UK's New Computerised Transit System (NCTS), two important things come back:
- An MRN (Master Reference Number) — an 18-character identifier that travels with the declaration through every message the customs systems exchange.
- A TAD (Transit Accompanying Document) — the printable paper that actually rides in the cab with the driver. It carries the MRN as a barcode and lists the consignment details.
If anyone along the route — the driver, a customs officer, an office of transit — needs to identify the movement, those are the two references that matter.
What data is needed to start
A T1 is not difficult to lodge if the data is clean. It is very hard to lodge if any of the following are missing or wrong:
- A GB EORI for the consignor and the consignee.
- A commercial invoice with commodity descriptions that actually classify to an HS code.
- Gross weight and net weight per consignment line, plus number and type of packages.
- The office of departure (a GB customs office or Inland Border Facility) and the office of destination (the customs office where the movement will be discharged).
- Route, expected start time and any seal numbers on the trailer.
For repeat shippers, most of this sits on file after the first movement — only the invoice-specific fields change per load.
The guarantee piece
Every T1 must be backed by a transit guarantee. The options are:
- CCG (Comprehensive Guarantee) — held by an authorised party, covers many movements at once. This is what regular operators use.
- TC31 — an individual cash guarantee, lodged per movement.
- TC33 — an individual voucher guarantee, used where a customer prefers to provide physical cover.
If you use a specialist T1 service, the provider normally holds CCG cover, so most of your movements are covered without any separate action by you. The guarantee is released automatically when the office of destination confirms discharge.
What a "good" T1 run looks like
The best way to tell whether your T1 flow is healthy is not how many declarations you lodge — it is how many discharge cleanly and on time. Any movement still open at the office of destination after its deadline becomes a risk to the guarantee. An active tracking discipline (chasing the destination office where needed, escalating before the deadline) is the part most providers skim over and the part that matters the most for a clean audit trail.
Get those three pillars right — clean data, the right guarantee, active discharge tracking — and a T1 stops being a paperwork problem and becomes a routine step in the move.