Peppol ID UK: how participant identifiers work

A Peppol ID, properly called a participant identifier, is your address on the Peppol network. It always has two parts, a four-digit scheme code and the identifier value, written as scheme:value. A UK business using its VAT number would typically look like 9932:gb123456789 (all numbers in this article are made up).

The anatomy of a Peppol ID

The rules are set by OpenPeppol's Policy for use of Identifiers (version 4.4.0, valid from 1 November 2025). Take this illustrative ID:

iso6523-actorid-upis::9932:gb123456789

Part	Example	Meaning
Meta scheme	iso6523-actorid-upis	Peppol's fixed "Participant Identifier Meta Scheme" (POLICY 5). Always the same.
Separator	::	Joins the meta scheme to the identifier in SMP URLs and many tools
Scheme code	9932	Which register the number comes from. 9932 is "United Kingdom VAT number"
Separator	:	Joins the scheme code to the value
Value	gb123456789	The identifier itself

Most of the time you will only see the short form, 9932:gb123456789. The policy notes that the meta scheme "may be omitted in documents because it is currently constant". The long form with :: is the format the SMP specification uses in lookup URLs, for example https://smp.example.org/iso6523-actorid-upis::9932:gb123456789.

Where the ID appears

The same identifier turns up in several places, written slightly differently in each:

• On the invoice (UBL): in the seller's and buyer's EndpointID, with the scheme code as an attribute: <cbc:EndpointID schemeID="9932">GB123456789</cbc:EndpointID>
• In the SMP: <ParticipantIdentifier scheme="iso6523-actorid-upis">9932:gb123456789</ParticipantIdentifier>
• In the message envelope (SBDH): <Identifier Authority="iso6523-actorid-upis">9932:gb123456789</Identifier>
• In the Peppol Directory: shown as 9932:gb123456789

Peppol BIS Billing 3.0 makes the electronic address mandatory for both sides. Rule PEPPOL-EN16931-R020 says "Seller electronic address MUST be provided" and PEPPOL-EN16931-R010 says the same for the buyer. If your customer's ID is missing from your customer record, the invoice will not validate.

Case, characters and length

From the policy:

• Case: "All Participant Identifier values have to be treated case insensitive even if the underlying scheme requires a case sensitive value." So 9932:GB123456789 equals 9932:gb123456789. The policy's own example: "0088:abc is equal to 0088:ABc", but "0088:abc is NOT equal to 0010:abc".
• Meta scheme case: iso6523-actorid-upis "is always case sensitive". Write it in lower case.
• Characters: values may use only letters, digits, -, ., _ and ~. No spaces. Write gb123456789, never GB 123 4567 89.
• Length: from 1 to 130 characters, not counting the scheme code.

For lookups, the policy requires the identifier to be lower-cased before it is hashed. That is why directories and lookup tools often show IDs in lower case.

Which scheme should a UK business use?

The scheme code must come from the official Peppol participant identifier scheme code list (version 9.7, July 2026). The codes most relevant to UK businesses are:

Code	Scheme	Typical UK use
9932	United Kingdom VAT number (GB:VAT)	Most VAT-registered UK businesses
0088	Global Location Number (GS1 GLN)	NHS trusts and many NHS suppliers
0060	D-U-N-S Number	Some large companies
0199	Legal Entity Identifier (LEI)	Financial and larger groups

There is no code for Companies House numbers on the list, and no separate code for Northern Ireland or the Isle of Man. For more detail, see Peppol EAS codes for the UK: 9932 and 0088.

GB prefix or no prefix?

The code list entry for 9932 gives no structure, example or validation rule. So it does not say whether the value should include the GB prefix. We searched the Peppol Directory on 20 October 2026. Most UK registrations under 9932 included it (9932:gb followed by nine digits), but a minority used nine digits on their own.

Those are two different identifiers. A sender looking up 9932:gb123456789 will not find a business registered as 9932:123456789. Until the UK publishes rules, check how each customer is actually registered rather than assuming.

Worked example

Acme Widgets Ltd (fictional) is VAT-registered as GB 123 4567 89 and connects through a certified provider.

1. Its provider registers the participant iso6523-actorid-upis::9932:gb123456789 in its SMP and, usually, publishes a business card to the Peppol Directory.
2. Acme gives customers its Peppol ID: 9932:gb123456789.
3. A customer's system puts <cbc:EndpointID schemeID="9932">GB123456789</cbc:EndpointID> in the buyer party of any invoice sent to Acme.
4. The customer's provider looks up that ID, finds Acme's provider and delivers the invoice.

What is not settled for the UK mandate

As of 20 October 2026, the government has confirmed Peppol as the core network. It has not published:

• which identifier scheme(s) UK businesses must or should register under
• whether 9932 values should include the GB prefix
• how VAT groups, divisions and branches should be identified
• whether the UK will request a new scheme code (for example for Companies House numbers)

The implementation roadmap is due at Budget 2026 on 28 October. We will update this guide when it is published.

What to do now

1. Ask your provider which Peppol ID(s) it has registered for you, character for character.
2. Collect your customers' Peppol IDs and store the scheme code and value in separate fields.
3. Strip spaces from VAT-based IDs, and be consistent about the GB prefix.
4. If you supply the NHS, check whether you also need a GLN-based (0088) ID.