How to onboard suppliers to e-invoicing in the UK

To onboard suppliers to e-invoicing, segment them by volume, publish your Peppol ID and invoicing rules, test with the biggest suppliers first and then move the rest in waves. Most suppliers will not need a separate system: they will send through their own accounting software and Access Point, using the Peppol network confirmed for the UK mandate starting April 2029.

Start now. The earlier suppliers send e-invoices, the sooner your accounts payable team stops keying bills.

What is confirmed

• E-invoicing is mandatory for VAT invoices from April 2029 (government consultation response).
• Peppol is the network: the GOV.UK Tax update 2026 summary says "the electronic procurement system Peppol will be the core interoperability network for e-invoicing in the UK."
• A decentralised model with no government portal.

Not yet confirmed: exemptions or phasing for small suppliers, and the treatment of non-VAT-registered suppliers' invoices beyond the general position that non-registered businesses will not have to adopt e-invoicing. Expect more in the Budget 2026 roadmap on 28 October 2026.

Step 1: get your own house in order

Before you contact suppliers:

• Register each buying entity on Peppol and confirm your Peppol ID. The Peppol code list includes scheme 9932 for UK VAT numbers.
• Check you appear in the Peppol Directory.
• Confirm your AP system can receive invoices and credit notes (see accounts payable e-invoicing).
• Decide what suppliers must include: PO number, buyer reference, contact, attachments.
• Clean your supplier master data (master data guide).

Step 2: segment your suppliers

Segment	Typical profile	Approach
Wave 1: high volume	Top suppliers by invoice count	Personal contact, joint testing, early go-live
Wave 2: medium	Regular suppliers with modern software	Email campaign, self-service instructions
Wave 3: long tail	Occasional or small suppliers	Standard letter, FAQ, reminder before 2029
Out of scope or special	Non-VAT-registered, overseas, self-billed	Keep a fallback channel; review case by case

Segment by invoice count, not spend. Many small invoices create more AP work than a few large ones.

Step 3: collect supplier data

Ask each supplier, ideally through an online form:

• legal name and UK VAT number (verify with HMRC's Check a UK VAT number);
• whether they are already on Peppol, and their Peppol ID;
• their accounting software, and whether it supports Peppol;
• an invoicing contact;
• their planned date to start sending.

Add Peppol ID fields to your new-supplier form so this becomes routine.

Step 4: communicate clearly

A short, specific message works best. Include:

1. Why: the UK mandate for VAT invoices from April 2029, and the benefits for them (faster approval, delivery confirmation).
2. What: "Please send invoices and credit notes over Peppol to [Peppol ID]."
3. Rules: PO number required, one invoice per PO, legal entity name.
4. When: your target date for their segment.
5. How: "Most accounting software can do this. Ask your provider about Peppol." Link them to our guide to checking Peppol support and small business guide.
6. Help: a named contact or mailbox.

Avoid telling suppliers which software or provider to use. On Peppol, any certified provider can reach you. That is the point of the four-corner model.

Step 5: test with wave 1

• Agree a test invoice and credit note with each supplier.
• Check data arrives correctly: VAT, totals, PO, attachments.
• Check matching and approval work end to end.
• If you use invoice responses, check the supplier receives them.
• Agree a switch-over date after which PDFs are no longer accepted from that supplier.

Step 6: roll out in waves and track progress

Track each supplier's status:

Status	Meaning
Not contacted
Contacted	Message sent
Responded	Data collected
Testing	Test invoice sent
Live	Sending production e-invoices
Exception	Out of scope or special handling

Report the percentage of invoice volume arriving via Peppol each month. That is the measure that matters.

Step 7: make it stick

• Add an e-invoicing clause to new contracts and purchase order terms, reviewed by your legal team.
• Stop accepting PDFs from live suppliers, with a polite redirect.
• Re-contact silent suppliers before each wave closes.

Common supplier objections

"Our software doesn't do Peppol." Ask them to check their provider's UK plans in writing. If there is no plan, they will need a solution by April 2029 for all their VAT-registered customers, not just you.

"We use your portal already." Explain that Peppol lets them connect once and reach every buyer on the network.

"We are not VAT-registered." They may be out of scope. Keep a fallback channel and note them as an exception.

"We'll wait until 2029." That is their right until the mandate starts. Explain the benefits of starting early and keep them in a later wave.

Public-sector buyers are ahead

If you are a public-sector buyer, many suppliers may already be familiar with Peppol. NHS Supply Chain requires suppliers to issue e-invoices through Peppol, according to the government's consultation response. See our NHS guide.

What to do now

• Confirm your Peppol ID and directory entry.
• Rank suppliers by invoice count and pick wave 1.
• Draft the supplier message and data form.
• Add supplier onboarding to your project plan.