Export Customs Clearance - Step-by-Step Procedure Guide

Exporting goods outside the European Union requires completing full export customs clearance. The procedure involves several stages - from filing an export declaration in the AES PLUS system, through the assignment of an MRN number, transport of goods to the port of exit, to the closure of the MRN and obtaining the export confirmation message confirming the export. Each of these stages has its own requirements, risks and pitfalls. In this guide, we walk through the entire procedure - step by step.

What Is Export Customs Clearance?

Export customs clearance is the set of customs formalities required when moving goods out of the customs territory of the European Union. It encompasses filing an export declaration, customs inspection (if the goods are selected for it), release of goods for export and - ultimately - confirmation that the goods have actually left EU territory.

The obligation to carry out customs clearance applies to all goods leaving the EU customs territory, regardless of their value (although simplified procedures apply to low-value consignments). This covers both exports to third countries (e.g., the USA, China, the United Kingdom) and to EU special territories (e.g., the Canary Islands, French overseas departments).

The purpose of the procedure is not only to control goods leaving the EU but also - from the exporter's perspective - to document the export for VAT purposes. Without properly completing the clearance and obtaining export confirmation, the exporter cannot apply the 0% VAT rate.

Step 1: Export Declaration and MRN Assignment

The export procedure begins with the filing of an electronic export declaration in the AES PLUS system (Automated Export System Plus) via the PUESC platform. The declaration is filed by the exporter or - far more commonly - by their customs representative (customs agent) acting under authorisation.

Data Required in the Declaration

The export declaration (message CC515C in AES PLUS nomenclature) must contain a range of mandatory data, including:

• Exporter data - EORI number, registered office, AEO status (if applicable)
• Consignee data - the foreign trading partner (buyer of the goods)
• Goods description - CN code (Combined Nomenclature), text description, quantity, weight, value
• Transport information - mode of transport, container number, booking reference number
• Customs office of exit - the seaport, airport or border crossing through which the goods will leave the EU
• Terms of delivery - Incoterms (e.g., FOB, CIF, EXW)
• Customs procedure - export procedure code (standard 1000 for normal export)

MRN Assignment

After positive verification, the AES PLUS system automatically assigns a unique MRN (Movement Reference Number) - an 18-character identifier that accompanies the shipment throughout the entire export chain. The exporter receives CC528C (acceptance and MRN allocation) followed by CC529C (release for export), signifying the customs office's approval for the goods to be moved out.

At this point, the goods are formally “released for export”, but the export procedure is not yet closed. Closure will only occur when the customs office of exit confirms that the goods have actually left the EU.

Step 2: Office of Export vs Office of Exit - A Key Distinction

One of the most common sources of confusion in the export procedure is the distinction between the office of export and the office of exit. These are two different customs offices performing different functions:

In a typical scenario of maritime export from Poland through the port of Hamburg or Rotterdam: the office of export is the Polish customs office (e.g., the customs office in Gdansk, Wroclaw or Warsaw), while the office of exit is the customs office at the foreign port (e.g., Hauptzollamt Hamburg-Hafen or the Dutch Douane Rotterdam).

This distinction is of fundamental importance for the MRN closure process. The office of exit closes the MRN based on information from the port system - confirming that the container with the given MRN has been loaded onto a vessel that has left the port. If this information does not reach the office of exit, the MRN remains open and the exporter does not receive the export confirmation.

Step 3: Transport of Goods to the Port of Exit

After obtaining release for export (message CC529C), the goods are transported to the office of exit - most commonly a seaport. At this stage, it is critical that the physical shipment (container) is correctly linked to the customs declaration (MRN).

For maritime export through European ports (Hamburg, Rotterdam, Antwerp, Bremerhaven and others), the container must be correctly registered in the port system. Every major European port uses its own management system, meaning different procedures, interfaces and documentation requirements.

Correct registration in the port system means that the data from the MRN (container number, weight, goods description) matches the data from the vessel manifest and the freight booking. If there are discrepancies - e.g., the container number has changed, the vessel has changed or the exporter data does not match - the port system will not automatically link the MRN to the physical container, blocking the closure of the procedure.

Step 4: MRN Closure in the Port System

This is the most important and most problematic stage of the entire export procedure. After the physical loading of the container onto the vessel and the vessel's departure from the port, the port system should automatically confirm the export and transmit this information to the customs office of exit. The office of exit in turn informs the office of export (in Poland), which generates the export confirmation message for the exporter.

In theory, this process is fully automatic. In practice, however, automatic MRN closure fails in approximately 5-15% of cases - depending on the port and the specifics of the shipment. The causes vary:

• Data discrepancy - the container number in the customs declaration does not match the number at the terminal (e.g., a last-minute container change)
• Vessel change - the container was transhipped to a different vessel than planned, and the manifest was not updated
• Missing manifest transmission - the carrier did not send or delayed sending the loading manifest to the port system
• Cargo consolidation - for LCL (Less than Container Load) shipments, matching customs data to the physical container is more complex
• Transhipment - goods are transhipped at an intermediate port, which can complicate tracking

In each of these cases, manual intervention is required - a submission to the port system with documents confirming loading (Bill of Lading, booking confirmation, manifest). This process requires access to the relevant system, knowledge of the specific port's procedures and often communication in a foreign language (German, Dutch, English).

Step 5: Receiving the Export Confirmation

The export confirmation message (in Poland: CC599C; in Germany: Ausgangsvermerk; in the Netherlands: confirmation of exit) is the official confirmation that the export procedure has been completed - the goods have left the territory of the European Union. It is generated electronically by the national AES customs system and delivered to the exporter through that country's portal (PUESC in Poland).

The export confirmation message contains:

• The MRN of the export declaration
• Exporter and consignee details
• Goods description and value
• Date of export confirmation
• Customs office of exit

The export confirmation message is a key tax document - it constitutes the basis for applying the 0% VAT rate on the export of goods (Art. 41(4) and (6a) of the Polish VAT Act). Without it, the exporter must declare the supply at the domestic rate of 23%, meaning significant funds are frozen.

Read more about the tax significance of the export confirmation in our article: 0% VAT on Export - Export Confirmation (CC599C) as Proof of Export.

Most Common Problems in the Export Procedure

Complications can arise at every stage of the procedure. Below we discuss the most common ones and their impact on the entire process.

1. Errors in the Export Declaration

An incorrect CN code, wrong container number, erroneous EORI - any of these errors can result in rejection of the declaration or, worse, problems at a later stage. The container number is particularly critical - if it does not match the data in the port system, automatic MRN closure will not occur.

2. Customs Inspection

The office of export may select a shipment for customs inspection - physical (opening the container) or documentary. An inspection delays the release of goods and may require additional documents to be provided. In extreme cases, it may lead to correction of the declaration or refusal of export.

3. Unclosed MRN in the Port System

This is the most common problem - the goods have physically left the EU, but the MRN has not been closed in the system. The exporter does not receive the export confirmation, even though the goods are already with the foreign buyer. The solution is intervention in the port system - manual or commissioned from a specialist. MRN closure via closemrn.com has an average filing time of 32 minutes, with a 2h order acceptance guarantee.

4. Communication Delays Between Customs Offices

Even after MRN closure in the port system, the export confirmation message may reach the exporter with a delay. This is due to the time needed for data exchange between the office of exit and the office of export (within the AES system). This time depends on the customs administrations involved and can range from a few days to even several months.

Tax Deadlines and Consequences of Delays

The export procedure does not end with the physical departure of the vessel from port. From a tax perspective, what matters is obtaining the export confirmation within a specific deadline, without which the exporter loses the right to the 0% VAT rate.

Under Art. 41(6)-(7) and (11) of the Polish VAT Act, the exporter has until the filing deadline for the tax return for the next accounting period after the month of delivery - in practice approximately 2 months from the end of the month of delivery. After exceeding this deadline, the supply must be declared at the domestic rate of 23%.

Timeline - Example

As you can see, a delay in MRN closure of even a few weeks can mean having to temporarily pay 23% VAT and freezing significant funds. For an export worth 500,000 PLN, that is 115,000 PLN in frozen tax.

FAQ - Export Customs Clearance

Legal basis: Regulation (EU) No 952/2013 of the European Parliament and of the Council of 9 October 2013 establishing the Union Customs Code (Art. 263-277). Commission Implementing Regulation (EU) 2015/2447 (Art. 329-334). Art. 41(4)-(11) of the Polish Act of 11 March 2004 on Tax on Goods and Services (consolidated text: Dz.U. 2025, item 775). This article is for informational purposes and does not constitute legal or tax advice.