What does an IOSS number look like?

An IOSS number is a VAT identification number that starts with the prefix "IM" followed by a string of digits, for example IM1234567890. It is unique to the registered seller or intermediary.

Where does the IOSS number go on a parcel?

It is not printed visibly on the parcel. The IOSS number is transmitted electronically in the customs declaration data, which protects it from being copied and misused by others.

Why must I keep my IOSS number confidential?

Because anyone who has it could use it to import goods VAT-free under your registration, which would leave you liable for the unpaid VAT. Only share it with trusted carriers or customs agents handling your genuine IOSS shipments.

Whose IOSS number do I use when selling on a marketplace?

For imported low-value sales where the marketplace is the deemed supplier, you use the marketplace's IOSS number as instructed, not your own. The marketplace collects and remits the VAT for those orders.

Glossary

IOSS Number

IOSS VAT identification number · IOSS ID

An IOSS number is the VAT identification number issued when you register for the EU Import One-Stop Shop scheme. It is included in the customs data of low-value parcels (€150 or less) to show that EU VAT has already been collected at checkout, allowing the goods to clear customs without import VAT being charged on delivery.

Last updated: June 2026

Key facts

An IOSS number is a special VAT identification number that begins with the prefix "IM" followed by digits.
It is transmitted electronically in the customs declaration data, not printed visibly on the parcel, to protect it from misuse.
The number tells customs that VAT on that consignment was already collected under IOSS, so no import VAT is due on delivery.
Marketplaces acting as deemed suppliers use their own IOSS number for the low-value imports they are responsible for.

What an IOSS number is

When a seller or intermediary registers for the Import One-Stop Shop, the tax authority issues an IOSS identification number. It is a distinct VAT identifier, formatted with an "IM" prefix, that is unique to the registered party and used solely for IOSS imports.

The number's job is to link a low-value import to a valid IOSS registration. When the parcel arrives at the EU border, the IOSS number in the electronic customs data signals that VAT was already charged to the customer at the point of sale, so customs releases the goods without collecting import VAT again.

How the IOSS number is used and protected

The IOSS number is provided to your carrier or customs declarant so it can be entered into the customs declaration for each eligible consignment. It is deliberately transmitted as data rather than printed on the outside of the box, because a leaked IOSS number can be abused by others to import goods VAT-free under your registration, leaving you liable.

For this reason, sellers must control who has access to their IOSS number and ensure it is only used for their own genuine IOSS sales. The registered party keeps records of all IOSS transactions and reports them in the monthly IOSS return tied to that number.

When you sell through a marketplace that is the deemed supplier for imported low-value goods, the marketplace applies its own IOSS number to those shipments. You should follow the marketplace's instructions on which IOSS number to put in the shipping and customs data so the VAT is correctly accounted for.

Example

A seller registered for IOSS receives a number such as IM1234567890. For a €30 parcel sent to Spain, that number is entered into the electronic customs declaration — not printed on the label — so the package clears customs in Spain with no import VAT charged to the buyer, because the VAT was already collected at checkout.

Why it matters for marketplace sellers

Your IOSS number must reach your carrier or customs declarant correctly for every eligible parcel; a missing or wrong number means the customer can be charged import VAT again on delivery.
Treat your IOSS number as sensitive — if it leaks, others can import under it and you can be left liable for the VAT, so restrict who can see and use it.
When a marketplace is the deemed supplier, use the marketplace's IOSS number for those orders exactly as instructed rather than your own.
Keep clear records of which sales were declared under your IOSS number, since you report them all in the monthly IOSS return.