What is the DUA (Single Administrative Document) and How Does It Work

If your company imports or exports goods, you have probably heard of the DUA (which in Spanish stands for Documento Único Aduanero, or Single Administrative Document). Understanding what the DUA is in customs and how it works is essential to grasp the customs clearance process in Spain and across the European Union. At SILE Customs Broker we explain everything you need to know, including the most important regulatory change of 2025: the replacement of the DUA by the new H1 electronic system.

What is the DUA in customs

The DUA, or Single Administrative Document, is the official declaration that importers and exporters must submit to customs so that their goods can move legally between countries. It is the central document of the customs clearance process in the European Union and has been the foundation of the system since its introduction in 1988.

It is called “single” because all the data needed by customs authorities to identify, value and classify the goods are grouped into one single form. Before its creation, each Member State used its own forms, which greatly complicated international trade.

The DUA customs declaration is mandatory for any import or export operation involving goods outside the European Union, and for certain special operations within it.

What is the DUA used for

The DUA fulfils several key functions within the customs process:

• Declaring goods to customs: it informs the Tax Agency about the type of product, its origin, value and destination.
• Calculating duties and taxes: based on the DUA data, customs duties, import VAT and other applicable taxes are determined.
• Accrediting customs clearance: once approved, the DUA authorises the legal entry or exit of goods from the customs territory.
• Justifying operations before the Tax Authority: it is the document that proves the non-EU origin of the goods and their correct taxation.

What information does the DUA contain

The Single Administrative Document captures all relevant operation data in a structured format. The most important fields include:

• Identification of the declarant and the importer or exporter
• Detailed description of the goods and tariff code (CN/TARIC)
• Country of origin and country of provenance
• Customs value of the goods
• Gross and net weight
• Requested customs procedure (definitive import, export, transit, etc.)
• Transport details and mode of transport used
• Amount of customs duties and taxes to be paid

All this information must be accurate and verifiable. An error in the import DUA can lead to penalties, delays in clearance or even the detention of goods at customs.

How the customs clearance process works with the DUA

The customs clearance process with the DUA follows a clear sequence, typically managed by a customs agent on behalf of the importer or exporter:

1. Receipt of documentation: the agent receives the commercial invoice, packing list, bill of lading or waybill and any other document required depending on the type of goods.
2. Tariff classification: the correct TARIC code is determined, which defines the duties and taxes applicable to that specific product.
3. Customs valuation: the customs value is calculated in accordance with the rules of the Union Customs Code.
4. Submission of the declaration: the agent submits the DUA to the Tax Agency through the electronic system.
5. Customs control: customs may automatically authorise clearance, request additional documentation or carry out a physical inspection of the goods.
6. Release: once the declaration is approved and duties settled, the release document is issued, authorising the collection of the goods.

The entire process can be completed within a few hours when the documentation is correct and the goods do not trigger any alerts in the risk analysis system of the Spanish Tax Agency.

Types of DUA by customs operation

Although we refer to the DUA as a single document, there are different forms depending on the type of operation:

• Import DUA: for the definitive introduction of goods into the EU customs territory from a third country.
• Export DUA: for the definitive departure of goods from EU territory.
• Transit DUA: for the movement of goods under customs supervision between different points without settling customs duties.
• Special procedures DUA: customs warehousing, inward processing, temporary admission, among others.

In all cases, understanding what the DUA is in customs comes down to the same logic: a formal declaration to the competent authority that enables the control and traceability of foreign trade.

2025 update: the H1 system replaces the DUA from 14 October

This is the most significant change for any company operating in foreign trade in the coming months. The Spanish Tax Agency has confirmed that as of 14 October 2025 the new H1 electronic system will come into force, definitively replacing the traditional DUA and the Customs Value Declaration DV1.

Here are the key points you need to know:

• The H1 is not a physical document: it is an electronic import customs declaration system. It does not exist in paper form or as a downloadable file.
• The paper DUA and DV1 are eliminated: both documents are abolished. The H1 integrates all the information previously collected separately in each of them.
• New valid documents: after clearance, the H1 system will only issue the Release document and the Import Certificate. These will be the only recognised customs documents.
• Mandatory for all imports: from that date, all import declarations must be processed exclusively through the H1 system.

This change directly affects importers, freight forwarders and customs agents, who will need to adapt their internal procedures before the established deadline. If your company carries out regular imports, it is essential to be aware of these developments well in advance.

Further information on customs modernisation is available on the European Union Customs Code portal.

How the H1 system differs from the DUA

The shift from the DUA to the H1 system is not simply a name change. It represents a fundamental transformation in how import customs clearance is managed:

• The DUA was a form (on paper or in electronic format). The H1 is an integrated digital declaration platform.
• The DUA produced a recognisable, archivable document. The H1 does not generate any “DUA document”: it only issues the Release and the Import Certificate.
• The Customs Value Declaration DV1, previously submitted separately for high-value goods, is absorbed into the new H1 system.
• The H1 system is aligned with the customs modernisation driven by the European Union under the e-Customs programme.

[INTERNAL LINK: SILE customs clearance services page]

Frequently asked questions about the DUA in customs

Who can submit the DUA or declare using the H1 system?

The customs declaration can be submitted by the importer or exporter themselves, but in practice it is handled by an authorised customs agent, also known as a customs representative. This professional acts on behalf of the operator and is responsible for the accuracy of the data declared to the Tax Agency.

Is the DUA the same as the import invoice?

No. The commercial invoice is a seller’s document that evidences the commercial transaction. The import DUA is the formal declaration to customs, prepared on the basis of the invoice and other operation documents. They are complementary documents, not equivalent ones.

What happens if there is an error in the DUA?

An error in the customs declaration can result in an incorrect duty assessment, penalties from the Tax Agency or the detention of goods at customs. This is why it is essential that the declaration is handled by a specialised customs agent with experience in the field.

When does the H1 system come into force?

The new H1 system comes into force on 14 October 2025, as communicated by the Spanish Tax Agency through an official circular. From that date, the paper DUA and the Customs Value Declaration DV1 will no longer be valid for import operations.

What documents does the H1 system issue after clearance?

After completing clearance with the H1 system, the only valid customs documents will be the Release — which authorises collection of the goods — and the Import Certificate. No document equivalent to the old paper DUA will be issued.

Manage the transition to the H1 system with SILE Customs Broker

The transition from the DUA to the H1 system is the most important regulatory change in customs in recent years for any importing company in Spain. Adapting on time is key to avoiding delays in clearance and ensuring compliance with the Tax Agency.

At SILE Customs Broker we have years of experience managing our clients’ customs clearance with rigour, precision and up-to-date knowledge of current regulations. Our team is fully prepared to operate with the new H1 system from its entry into force on 14 October 2025.

If you have questions about how this change will affect your company or want to make sure your imports are not disrupted, contact us. We will advise you with no obligation and support you throughout the entire transition.