An export invoice must include the parties' details with EORI numbers, a description of the goods with the HS code, the value, and the Incoterms — this is the basis of the export declaration.
Contents
In brief — what you will learn
- ✓ How to prepare the process and the documents
- ✓ How the declaration and inspection work
- ✓ How to maintain compliance and settlements
How to prepare the process and the documents
The export invoice is one of the documents underpinning the export declaration in the CDS system, so its data must match the declaration exactly. It should include the full details of the seller and buyer, including EORI numbers, an exact description of the goods with the HS code, the transaction value, the currency, and the agreed delivery terms (Incoterms). A discrepancy between the invoice and the declaration is one of the most common reasons a shipment is held for clarification.
Split of responsibilities between the parties
Minimum data set for the declaration
Easy Clearance specialises in import and export to the UK.
How the declaration and inspection work
A consistent approach to documentation shortens clearance time, reduces corrections after the declaration is filed, and lowers the risk of costs arising from the cargo being held or tax obligations being wrongly assigned. For export declarations, a precise split of roles between the importer, the exporter and the customs representative is decisive.
Operational stages from pre-notification to release
The export declaration process goes through successive stages: pre-notifying the cargo with the carrier, preparing and filing the declaration in the AES (PL) or CDS (UK) system, document verification by the customs authority, release of the goods, and obtaining the EAD document with the MRN. The EAD document must accompany the shipment until it physically leaves the customs territory, and its number should be kept as proof of export for VAT settlement purposes.
The most common risk points and how to limit them
The most common errors in the export process are: a mismatch between the value on the invoice and in the customs declaration, a missing EORI number for the buyer, incorrect CN classification of the goods, and omitting the Incoterms. It is worth introducing an internal document-completeness check before the vehicle is presented for loading, using a standardised checklist approved by the compliance department or the customs agency.
How to maintain compliance and settlements
Every step of the export process should be documented: from classifying the goods, through the customs value, to confirmation that the relevant declarations have been filed. For companies operating regularly in the UK–PL market, keeping complete documentation for the required retention period is particularly important.
Record-keeping, corrections and evidence of due diligence
The customs authorities both in Poland (KAS) and in the United Kingdom (HMRC) require complete documentation to be kept for at least 5 years from the end of the year in which the transaction took place. The record-keeping checklist should cover: the original export invoice, the EAD or MRN confirmation, CMR transport documents, Incoterms documentation, and correspondence with the customs agency. If a declaration is corrected, keep a revision trail with the date the change was made, as evidence of due diligence during an inspection.
Working with a customs agency and internal audit
Working with an experienced customs agency helps reduce the risk of errors in classifying and valuing the goods, and speeds up procedures thanks to direct access to the CDS and AES systems. It is worth carrying out an internal audit of export processes every quarter, checking the consistency of data between invoices and customs declarations, and updating checklists in line with current KAS and HMRC notices.
Summary
In summary: for 'how to prepare an export invoice', the key is to run the process according to current official guidance, with a clear split of responsibilities and documentation of every decision. This approach reduces delays, cuts the number of corrections and makes it easier to defend the settlements during an inspection. If any requirement is unclear, check the current KAS or HMRC guidance before submitting the customs declaration.
Legal basis and sources
If the rules or system notices are updated, check the current GOV.UK or KAS guidance before submitting a declaration.
Frequently asked questions
What mandatory elements should an export invoice to the United Kingdom include?
An export invoice to the UK must include: the full details of the seller and buyer with EORI numbers, a description of the goods with the CN or HS code, the value in the transaction currency, the Incoterms, the country of origin of the goods, and the customs declaration reference number. Missing any of these elements can result in the cargo being held or the declaration being rejected by the CDS system.
What is the difference between an EORI number and a tax ID (NIP) number when exporting goods?
The EORI (Economic Operators Registration and Identification) number is the required customs identifier for trade with non-EU countries, including the United Kingdom. The NIP is the Polish tax identifier used for VAT settlements within the EU. Export customs declarations always require the EORI of both the exporter and the importer — a missing buyer EORI number is one of the most common reasons a declaration is rejected.
Which electronic systems handle export declarations in Poland and in the United Kingdom?
In Poland, export declarations are filed through the AES (Automated Export System) administered by KAS. In the United Kingdom, HMRC's CDS (Customs Declaration Service) is in use, having replaced the earlier CHIEF system. Confirmation of a correctly filed declaration is the EAD (Export Accompanying Document) with an MRN number, which must accompany the goods until they leave the customs territory.
How long must export documentation be kept under KAS and HMRC rules?
Both KAS in Poland and HMRC in the United Kingdom require complete customs and commercial documentation to be kept for at least 5 years from the end of the calendar year in which the transaction took place. The documentation should include invoices, CMR lists, EAD/MRN confirmations, and correspondence with the customs agency. Failing to keep records can result in financial penalties during an inspection.
When is it worth using an experienced customs agency for exports to the UK?
Using a customs agency is especially advisable when exporting regulated goods (food, medical devices, dual-use goods), for first transactions into the UK market, and for shipments requiring the T1 procedure or Regime 42. An experienced customs agency provides access to the CDS and AES systems, checks the HS classification, and minimises the risk of errors leading to delays or financial penalties.
Related guides
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