# How to onboard suppliers to e-invoicing in the UK

> A step-by-step plan for onboarding UK suppliers to Peppol e-invoicing before April 2029: segmentation, communications, data collection, testing and follow-up.

- Canonical URL: https://einvoices.uk/news/supplier-onboarding-e-invoicing
- Published: 20 October 2026 (2026-10-20)
- Last updated: 20 October 2026 (2026-10-20) (not updated since publication)
- Author: Floris Lindenaar, Editor, e-invoicing expert (https://einvoices.uk/authors/floris-lindenaar)
- Publisher: einvoices.uk (https://einvoices.uk)
- Type: Guide
- Topics: Finance teams, Peppol, 2029 mandate, Small business
- Language: en-GB (UK English); covers the United Kingdom

## Sources

- [Tax update 2026: simplification, modernisation and fairness summary](https://www.gov.uk/government/publications/summary-of-tax-update-2026-simplification-modernisation-and-fairness/tax-update-2026-simplification-modernisation-and-fairness-summary)
- [Promoting electronic invoicing across UK businesses and the public sector: consultation response](https://www.gov.uk/government/consultations/promoting-electronic-invoicing-across-uk-businesses-and-the-public-sector/outcome/promoting-electronic-invoicing-across-uk-businesses-and-the-public-sector-consultation-response)
- [OpenPeppol eDEC Code Lists](https://docs.peppol.eu/edelivery/codelists/)
- [Check a UK VAT number](https://www.gov.uk/check-uk-vat-number)

---

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](https://einvoices.uk/news/peppol-participant-id-uk). The Peppol code list includes scheme 9932 for UK VAT numbers.
- [ ] Check you appear in the [Peppol Directory](https://einvoices.uk/news/peppol-directory-lookup-uk).
- [ ] Confirm your AP system can receive invoices **and** credit notes (see [accounts payable e-invoicing](https://einvoices.uk/news/accounts-payable-e-invoicing-uk)).
- [ ] Decide what suppliers must include: PO number, [buyer reference](https://einvoices.uk/news/purchase-order-reference-buyer-reference-peppol), contact, attachments.
- [ ] Clean your supplier master data ([master data guide](https://einvoices.uk/news/master-data-cleanup-e-invoicing)).

## 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](https://www.gov.uk/check-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](https://einvoices.uk/news/check-accounting-software-peppol-support) and [small business guide](https://einvoices.uk/news/e-invoicing-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](https://einvoices.uk/news/four-corner-model-explained).

## 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](https://einvoices.uk/news/peppol-invoice-response-message-level-response), 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](https://einvoices.uk/news/nhs-peppol-e-invoicing-suppliers).

## 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](https://einvoices.uk/news/e-invoicing-project-plan-finance-teams).

## Frequently asked questions

### How do I get my suppliers to send e-invoices?

Segment suppliers by volume, tell them your Peppol ID and invoicing requirements, give them a date to start, test with the largest first, and follow up with those not yet sending. Most suppliers will connect through their own accounting software.

### Can I force suppliers to use Peppol before 2029?

You can set it as a commercial requirement in contracts and purchase orders, as some public-sector buyers already do, but the legal mandate for VAT invoices does not start until April 2029.

### What if a small supplier cannot send e-invoices?

Find out why. Some will not be VAT-registered and may be out of scope. Others may just need to switch on a feature in their software. Keep a fallback channel for out-of-scope documents.

### Should suppliers use a buyer portal instead of Peppol?

Peppol is confirmed as the UK network, so a supplier connected once can reach every Peppol buyer. Asking suppliers to key invoices into separate portals is likely to be less attractive to them after 2029.

---

How to cite: "How to onboard suppliers to e-invoicing in the UK", einvoices.uk, 20 October 2026, https://einvoices.uk/news/supplier-onboarding-e-invoicing

einvoices.uk is an independent publication and is not affiliated with HMRC or the UK Government. Nothing here is tax advice; check the sources and official GOV.UK guidance before acting.