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

The next step depends on the cause and procedural stage. CloseMRN can compare documents with available statuses, identify a confirmed discrepancy and agree an amendment or repeat registration within the service scope. Formal customs contact in another party’s case requires appropriate authority.

Step 5: Receiving the Export Confirmation

In Poland’s AES/ECS2 PLUS, the office of export sends CC599C to the declarant after receiving results from the office of exit. Check the content and result code: refusal to allow exit may also generate a CC599C with B1. For port-only handling, the agency responsible for export normally receives the final message and passes it to its client.

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

For a supply subject to Polish VAT, a missing message does not automatically rule out the 0% rate. Assess the evidence of exit, its link to the supply and the deadlines in Article 41(6)–(9) and (11) of the Polish VAT Act. If the conditions are not met, the rate applicable to the goods must be considered; it is not always 23%. Confirm the treatment of the specific supply with your accountant.

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

If the exit result is missing, review the declaration, actual route and available documents. CloseMRN reviews MRN cases and recommends action within an agreed scope; formal representation requires authority. Preparing a submission does not guarantee export confirmation within a fixed time.

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.

Document deadlines under Polish VAT rules

Article 41(6)–(9) and (11) of the Polish VAT Act sets conditions and deadlines for export evidence, reporting in the following period and later corrections. The accounting period, proof of the export procedure and identification of the goods matter. A missing XML file does not automatically trigger 23% VAT: the applicable rate and treatment depend on the goods and the conditions of the supply.

Review the documents with your accountant. For operational help, send the MRN and transport history for an open MRN review. We do not promise confirmation or a tax outcome within a set time.

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.

PUESC: AES/ECS2 PLUS · Polish VAT Act, Article 41