Z Number (ZAPP) — Export Registration in Hamburg Port
The Z Number (Z-Nummer, short for Zollnummer) is the central export registration number in the Port of Hamburg, assigned by the ZAPP system (Zoll-Ausfuhrüberwachung im Paperless Port) operated by DAKOSY AG. Without a valid Z Number, your container cannot be properly linked to the customs declaration in Hamburg — which means no MRN closure, no CC599C / IE599 export confirmation, and no basis for applying the 0% VAT rate. This guide explains how the Z Number works, how to obtain one, and how ZAPP integrates with Hamburg's port infrastructure to close your MRN.
What is a Z Number?
Z Number (German: Z-Nummer or Zollnummer) is a unique export registration identifier assigned by the ZAPP platform in the Port of Hamburg. ZAPP stands for Zoll-Ausfuhrüberwachung im Paperless Port — a customs registration process portal integrated into the DAKOSY Port Community System. The Z Number links the customs export declaration (MRN from the AES/ATLAS system) with the physical container operations at Hamburg port terminals.
When a port agent, freight forwarder, or customs broker registers an export container in ZAPP, the system verifies the MRN status in ATLAS, matches the container and booking data, and assigns a unique Z Number. From that moment, the terminal operator (HHLA or Eurogate) knows that the container has an active customs declaration and can be processed for vessel loading.
The Z Number serves the same fundamental purpose as the BHT Number in Bremerhaven and the WHT Number in Wilhelmshaven. Each major German container port operates its own registration system — Hamburg uses DAKOSY/ZAPP, Bremerhaven uses BHT, and Wilhelmshaven uses WHT. The underlying logic is identical: without port-level export registration, the customs system has no way of confirming that goods have physically left the EU.
ZAPP and DAKOSY — Hamburg's Port Systems
DAKOSY AG (Datenkommunikationssystem AG) is the operator of Hamburg's Port Community System (PCS), connecting over 2,000 companies and institutions since 1982. DAKOSY provides the digital backbone for all commercial and customs-related communication in the Port of Hamburg — from shipping lines and terminal operators to customs authorities, freight forwarders, and trucking companies.
Within DAKOSY, several modules are relevant for export operations:
- ZAPP (Zoll-Ausfuhrüberwachung im Paperless Port) — the customs registration module that assigns Z Numbers and manages the link between MRN and container operations. ZAPP is the primary interface for export registration in Hamburg.
- EMP (Export Management Platform) — the broader export management platform handling port orders, vessel allocation, and loading confirmation. EMP integrates with ZAPP to automate the export workflow.
- ATLAS-AES interface — direct connection between DAKOSY and the German customs system ATLAS, enabling real-time status exchange for export declarations and MRN processing.
DAKOSY ZAPP provides real-time container status tracking (Containerstatus in Echtzeit) and automatic integration with the ATLAS customs system. When a container is loaded onto a vessel and the terminal confirms this in DAKOSY, the system automatically notifies ATLAS, triggering the MRN closure sequence.
Z Number, B Number, S Number — Differences
In the Port of Hamburg, the DAKOSY system uses three types of reference numbers in the export process. Understanding the distinction is important because port agents and terminal operators may reference any of them in their communications.
| Number Type | German Name | Purpose | Assigned By |
|---|---|---|---|
| Z Number | Z-Nummer (Zollnummer) | Main export registration number linking MRN to container operations; required for MRN closure | ZAPP (DAKOSY) |
| B Number | B-Nummer | Additional port reference number in Hamburg | DAKOSY EMP |
| S Number | S-Nummer (vessel reference) | Vessel-related number used for vessel allocation and loading schedules at the terminal | DAKOSY / Terminal |
From an exporter's perspective, the Z Number is the most important — it is the one that directly links your customs declaration (MRN) to the container and triggers the automated MRN closure process. The B Number and S Number are supporting references used internally by the port and terminal operators.
How Z Number Registration Works
Obtaining a Z Number and closing your MRN at the Port of Hamburg follows a defined process. Below is an overview of the key stages, from data preparation to receiving the CC599C export confirmation.
Data preparation
The registration process begins with gathering export data — the MRN, shipping line booking reference, container number, vessel information, and cargo details. All data must be consistent between the customs declaration and the booking confirmation — discrepancies are the leading cause of MRN closure failures in Hamburg.
ZAPP registration by a specialist
ZAPP registration requires a registered DAKOSY account and knowledge of Hamburg port procedures. The export data is entered into the ZAPP system by an authorized agent who manages the process end-to-end.
Automated validation
Once the export registration (Ausfuhranmeldung) is submitted, ZAPP automatically verifies the MRN status in ATLAS and cross-checks the container data with the booking. If there are discrepancies, the system raises a validation error and the registration cannot proceed until the data is corrected.
Z Number assignment
After successful validation, ZAPP automatically assigns a unique Z Number (Z-Nummer). This number confirms that the export container is registered in Hamburg's port system and linked to a valid customs declaration.
Terminal processing
The registration data is forwarded to the designated terminal (HHLA or Eurogate). The terminal accepts the container at gate-in, verifies it against the ZAPP registration, and schedules it for loading according to the vessel plan.
Loading → ATLAS notification → MRN Closure → CC599C
After the container is physically loaded onto the vessel, the terminal confirms this in DAKOSY. DAKOSY/ZAPP automatically transmits the loading confirmation to the German customs system ATLAS, initiating MRN closure. ATLAS generates the CC599C message (formerly IE599) and sends it to the customs office of export. In the case of Polish export declarations, the CC599C is forwarded to the Polish customs system (PUESC).
HHLA and Eurogate Terminals
The Port of Hamburg is served by two major terminal operators, each running multiple container terminals. All terminals are fully integrated with DAKOSY/ZAPP for export operations.
| Terminal | Operator | Type | Key Features |
|---|---|---|---|
| CTB (Container Terminal Burchardkai) | HHLA | Container | Hamburg's largest terminal; 4 berths; wide range of shipping lines |
| CTA (Container Terminal Altenwerder) | HHLA | Container (automated) | One of Europe's most automated terminals; AGV transport system |
| CTT (Container Terminal Tollerort) | HHLA | Container | Specializes in feeder services and Baltic/Scandinavia routes |
| Eurogate CTH | Eurogate | Container | Major deep-water terminal; handles largest vessel classes |
| UNIKAI | HHLA | Multipurpose | Ro-ro, breakbulk, project cargo; also integrated with ZAPP |
Both HHLA and Eurogate terminals are fully connected to DAKOSY. When you register an export in ZAPP, the data is automatically routed to the correct terminal based on the booking information. The terminal uses the Z Number to identify which containers have valid customs registrations and should be cleared for vessel loading.
FAQ — Frequently Asked Questions about Z Number
What is a Z Number in the Port of Hamburg?
A Z Number (Z-Nummer, Zollnummer) is a unique export registration number assigned by the ZAPP system (DAKOSY AG) in the Port of Hamburg. It links your customs declaration (MRN) to the physical container operations at the terminal and is required for automated MRN closure.
What is the difference between Z-Nummer, B-Nummer, and S-Nummer?
In Hamburg three port reference numbers exist: Z-Nummer, B-Nummer and S-Nummer. The Z Number is the most important for MRN closure.
How long is a Z Number valid?
A Z Number is valid for the duration of the specific export booking. After the container is loaded and the MRN is closed, the Z Number expires. Each new export shipment requires a new Z Number.
Can I get a Z Number without DAKOSY access?
Most international exporters commission a port agent or use specialized services (like potwierdz-wywoz.pl) to handle the ZAPP registration on their behalf, as the process requires knowledge of Hamburg port procedures and the German-language DAKOSY interface.
What happens if I do not register in ZAPP?
Without ZAPP registration, the terminal cannot link your container to the customs declaration (MRN). The container may not be loaded, or even if loaded, the MRN will not be closed automatically — resulting in no CC599C/IE599 and the inability to apply the 0% VAT rate on your export invoice.
Legal basis: Art. 334 of Commission Implementing Regulation (EU) 2015/2447. Information about DAKOSY and ZAPP based on official DAKOSY AG documentation and HHLA/Eurogate terminal operator guidelines. Legal status as of March 2026.