T1 & MRN explained: a simple guide to UK–EU customs documents

If you move goods between the United Kingdom and Europe, two terms come up again and again: T1 and MRN. They sound technical, but the idea behind them is simple — and understanding them can be the difference between a shipment that flows smoothly and one that sits stuck at a border post.

In this guide we'll explain what each one is, when you actually need them, and how to keep your cargo moving.

What is a T1 document?

A T1 (also called a transit declaration or T1 transit document) is a customs document that lets goods move across customs territories without duties and taxes being paid up front. Instead, those charges are suspended until the goods reach their final destination and are formally cleared there.

It's most often used when cargo passes through one or more countries on the way to where it's actually going. For example, goods travelling from the UK across France and Germany to a final buyer in Poland can move under a single T1 rather than being cleared at every border.

In short: a T1 keeps your goods "in transit" so they don't get taxed at every country they pass through — only at the end.

What is an MRN?

An MRN — Movement Reference Number — is the unique 18-character ID that customs assigns to a declaration once it's lodged in the system. Think of it as the tracking number for your customs paperwork.

Whenever you submit an export, import or transit declaration (including a T1), the system issues an MRN. Carriers and border officers use it to pull up your declaration instantly, which is why you'll often be asked to have it ready at check-in or at the border.

When do you need them?

• You're moving goods through the EU to a final destination beyond the first country of entry — a T1 covers the transit leg.
• Your cargo isn't yet customs-cleared and needs to travel inland before clearance.
• A carrier or port asks for an MRN to confirm your declaration is in the system before loading.
• You're shipping between Great Britain and the EU post-Brexit, where declarations are now required in both directions.

How to avoid delays at the border

Most border hold-ups come down to paperwork that's missing, incomplete or inconsistent. A few habits prevent the majority of problems:

1. Get your documents ready early

Prepare the T1 and any supporting paperwork before the vehicle arrives at the port, not when it's already in the queue.

2. Keep your commodity codes accurate

The right HS (commodity) code determines duties and controls. An incorrect code is one of the most common reasons cargo gets flagged.

3. Have the MRN to hand

Make sure the driver or carrier has the MRN — printed or digital — so officials can verify the declaration in seconds.

How Al-SQR Express handles this for you

The good news: you don't have to become a customs expert. Our in-house team prepares export and import declarations, raises T1 transit documents, and provides the MRN for every movement — so your cargo clears the border without the stress.

Whether you're shipping by air, sea or road, we make sure the paperwork keeps pace with the goods.