How to Prepare Customs Documents for UK Import — Complete Checklist

Importing goods into the United Kingdom after Brexit involves a set of mandatory customs documents that every carrier, freight forwarder and importer must submit correctly and on time. Mistakes in paperwork are the single biggest cause of delays at the UK border — and delays cost money. This guide covers every document you need, when to submit it, and what to watch out for.

Why Customs Documentation Matters More Than Ever

Before Brexit, goods moving between Poland and the UK travelled under EU free circulation rules — no customs declarations required. Since 1 January 2021, every commercial shipment crossing the UK border needs a full customs declaration. For carriers who previously never touched a customs form, the learning curve has been steep.

The UK operates its Customs Declaration Service (CDS) — the central system where all import and export entries are lodged. Understanding which documents feed into a CDS declaration is essential whether you handle customs in-house or work with an agent.

Core Documents Required for UK Import

1. Commercial Invoice

The invoice is the foundation of every customs declaration. It must show:

• Full name and address of seller and buyer
• Description of goods (precise enough to assign a commodity code)
• Quantity, unit price and total value in the transaction currency
• Country of origin
• Incoterms (e.g. DAP, DDP, CPT)

Vague descriptions like “various goods” or “spare parts” will trigger queries from HMRC and delay clearance.

2. Packing List

Where the invoice shows value, the packing list shows physical content: number of packages, gross and net weight per package, dimensions and any special handling markings. HMRC customs officers use it to verify the consignment against the declaration.

3. CMR Consignment Note

For road transport, the CMR note is the contract of carriage between the sender, carrier and consignee. Box 8 (customs) and Box 13 (arrival date) are particularly scrutinised during border checks. Always carry the original signed CMR with the vehicle.

4. EORI Number

Both the importer and exporter need an EORI (Economic Operators Registration and Identification) number. UK importers need a GB EORI; Polish exporters need an EU EORI. Without an EORI the declaration cannot be lodged. Apply well before your first shipment rather than on the day — check the current processing time on GOV.UK when you apply.

5. Commodity Code (HS/UK Trade Tariff)

This is not a physical document but a 10-digit code that every import declaration requires. The wrong code can mean the wrong duty rate or triggering a prohibited goods alert. Use the UK Trade Tariff to verify codes before lodging.

6. Import Declaration (lodged in CDS)

The full import declaration is lodged in the Customs Declaration Service. Your customs agent or in-house declarant uses the documents above to complete it, and CDS returns a Movement Reference Number (MRN) that links the consignment together in the system. For accompanied road freight the MRN feeds into a Goods Movement Reference (GMR) in GVMS, which the driver presents at the port.

Do not confuse this with the entry summary declaration below. The import declaration is the customs declaration — it establishes the procedure, the duty and the import VAT. The ENS is a separate safety and security declaration, filed by a different party, on a different deadline. Both are usually required; one never substitutes for the other.

7. ENS — Entry Summary Declaration

Since 31 January 2025, goods imported from the EU to Great Britain must be covered by a safety and security declaration — the entry summary declaration, lodged in the S&S GB system. It is a risk-assessment filing, not a customs entry, and validation returns its own movement reference number.

The legal duty to lodge the ENS sits with the carrier — the operator of the active means of transport bringing the goods in. A third party may submit it with the carrier’s knowledge and consent, but liability for timely submission stays with the carrier. For accompanied RoRo that means the haulage company, not the importer.

Deadlines run from arrival, not departure, and differ by mode:

• Road via the Channel Tunnel: at least 1 hour before arrival at the Eurotunnel terminal
• RoRo, accompanied and unaccompanied: at least 2 hours before arrival
• Short sea journeys: at least 2 hours before arrival
• Maritime containerised: 24 hours before loading at the port of departure
• Air, short-haul (under 4 hours): at the time of actual take-off
• Air, long-haul (4 hours or more): at least 4 hours before arrival

Declarations can be submitted up to 200 days in advance, so there is no reason to leave it to the last hour.

8. Proof of Origin (EUR.1 or REX)

If your goods qualify for preferential tariff treatment under the UK-EU Trade and Cooperation Agreement (TCA), you can avoid import duty. To claim preference you need either a EUR.1 movement certificate or a supplier’s declaration with a REX statement of origin. Origin rules are product-specific — incorrect claims trigger post-clearance audits and duty demands.

How to Make an Import Declaration: Step by Step

The documents above are inputs. The declaration is the act. Here is the sequence GOV.UK expects a GB importer to follow, and the decisions that actually change what you pay.

1. Get a GB EORI number. Nothing can be lodged without one. If you are also moving goods to or from Northern Ireland you may need a second, XI-prefixed number.
2. Decide who declares — and under which form of representation. This is the step most importers skim, and it carries real liability. Under direct representation the agent declares in your name and you alone are liable for the customs debt. Under indirect representation the agent declares in their own name on your behalf, and the two of you are jointly and severally liable. An agent cannot act without written instructions from you, and those instructions must state which form applies. Appointing an agent does not remove your own due-diligence duty.
3. Classify the goods. Find the 10-digit commodity code in the UK Trade Tariff before the goods ship. The code drives the duty rate, the VAT rate, and whether a licence, quota or control applies.
4. Work out the customs value. Method 1, the transaction value, is the default; the other methods apply in a fixed order when it cannot be used. Freight and insurance costs to the UK border usually form part of the value, so the Incoterm on your invoice changes the figure.
5. Check the reliefs and deferrals before you declare, not after. Preferential origin under the UK–EU TCA, Returned Goods Relief, inward processing, temporary admission and customs warehousing all have to be claimed on the declaration itself. Postponed VAT accounting lets you account for import VAT on your VAT return instead of paying it at the border; a duty deferment account moves the duty payment to the following month.
6. Choose the declaration route. A full frontier declaration is lodged in CDS before the goods are released. Alternatively, an authorisation for the Simplified Customs Declaration Process lets you release goods on a simplified frontier declaration or an entry in your own records, then follow up with a supplementary declaration. Under SCDP, supplementary declarations must be accepted and finalised by CDS by the tenth calendar day of the month following the end of the reporting period, the final supplementary declaration follows on the eleventh, and duty is taken from the deferment account on the sixteenth. Excise goods run on fortnightly reporting periods, and supplementary declarations are waived for goods entering a customs warehouse or a freeport site.
7. Lodge in CDS and move the goods. The accepted declaration returns an MRN. For accompanied RoRo, that MRN goes into a Goods Movement Reference in GVMS before the vehicle checks in.
8. Keep the records for 4 years. HMRC requires records of all traded goods declared to it to be kept for four years — invoices, the declaration, the C79 import VAT certificate and any preference evidence. Electronic storage is allowed, but paper originals bearing stamps or watermarks, such as preference certificates, must be kept as paper.

If the volume is low and the goods are simple, an in-house declarant on a full frontier declaration is workable. Once you are running regular consignments, mixed commodity codes, or anything under a special procedure, the arithmetic changes — which is the point of the comparison in the next section.

Licences, Permits and Additional Certificates

Certain product categories require additional documentation:

• Food and animal products: Health certificate, veterinary inspection, CITES permit (if applicable)
• Plants and plant products: Phytosanitary certificate
• Chemicals: Safety Data Sheet, REACH compliance statement
• Firearms, weapons: Import licence from the Home Office
• Medicines and medical devices: MHRA authorisation

Common Document Errors and How to Avoid Them

Using a Customs Agent vs. Doing It Yourself

Smaller importers often find that the cost of mistakes far exceeds the agent’s fee. A qualified customs broker handles declaration lodging, tariff classification, duty calculation and communication with HMRC on your behalf. They also carry professional indemnity insurance against errors.

If you are importing regularly on the PL–UK corridor, the practical question is who lodges the CDS entry at 2am when a trailer is already rolling. A dedicated UK import clearance desk handles the declaration, the classification and the time-critical ENS and GMR submissions for road carriers, which is usually where in-house teams run out of hours rather than out of knowledge.

For the declaration mechanics themselves, see our walkthrough of CDS import declarations.

Key Takeaways

• Every UK import needs: commercial invoice, packing list, CMR (road), EORI, commodity code, import declaration and ENS
• Origin documents (EUR.1 / REX) are optional but save significant duty costs under the TCA
• Late or incorrect ENS is the most common cause of port delays for road carriers
• Get your commodity codes right before the shipment — not after the border hold
• The import declaration and the ENS are two different filings, on two different deadlines, and the ENS is legally the carrier’s responsibility
• Choose direct or indirect representation deliberately — indirect makes the agent jointly and severally liable for the customs debt, direct does not
• Keep customs records for 4 years

Mini-FAQ

Is an entry summary declaration the same as an import declaration? No. The ENS is a safety and security declaration lodged before arrival, and the legal duty to submit it sits with the carrier. The import declaration is the customs entry lodged in CDS that establishes the procedure, duty and import VAT. Both are normally needed.

How long do I have to submit a supplementary declaration? Under the Simplified Customs Declaration Process, supplementary declarations must be accepted and finalised by CDS by the tenth calendar day of the month following the end of the reporting period; the final supplementary declaration follows on the eleventh, and deferment accounts are debited on the sixteenth.

If I use a customs agent, who is liable? It depends on the representation. Under direct representation you are solely liable for the customs debt. Under indirect representation you and the agent are jointly and severally liable. Either way you remain responsible for due diligence on your declarations.

How long must I keep import records? Four years for records of traded goods declared to HMRC, including the commercial invoice, the declaration and your C79 import VAT certificate.

Sources (gov.uk): Import goods into the UK: step by step; Safety and security import requirements: entry summary declarations; Simplified Customs Declaration Process: supplementary declarations; Customs debt liability; Get someone to deal with customs for you; Archiving your trade documents.

Last updated: 19 August 2026. UK customs requirements are set by HMRC — always verify current rules on GOV.UK before acting.