# E-invoicing with an ERP system: what to ask and how to plan

> How to plan UK Peppol e-invoicing on an ERP system: integration options, the questions to ask your ERP supplier or partner, data mapping and project risks.

- Canonical URL: https://einvoices.uk/news/e-invoicing-erp-systems-uk
- Published: 20 October 2026 (2026-10-20)
- Last updated: 21 October 2026 (2026-10-21)
- Author: Floris Lindenaar, Editor, e-invoicing expert (https://einvoices.uk/authors/floris-lindenaar)
- Publisher: einvoices.uk (https://einvoices.uk)
- Type: Guide
- Topics: Software, Finance teams, Peppol, Technical
- 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)
- [Peppol BIS Billing 3.0](https://docs.peppol.eu/poacc/billing/3.0/)
- [Peppol Certified Service Providers - OpenPeppol](https://peppol.org/members/peppol-certified-service-providers/)

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If your business runs an ERP system, UK e-invoicing is an **integration project**: your ERP must turn VAT invoices into Peppol e-invoices, hand them to an Access Point, and import supplier e-invoices into accounts payable, ready for **April 2029**. Whether that is a configuration change or a significant build depends on your ERP version, add-ons and how many invoicing systems you have.

This guide does not assess or name any ERP product. Capabilities vary by edition, version, region and licence, and change frequently. Instead, it sets out the options, the questions to put to your ERP supplier or partner, and the risks we see in ERP projects.

## What is confirmed

- E-invoicing is mandatory for VAT invoices from April 2029 (government consultation response).
- Decentralised model, with invoices exchanged between businesses through service providers.
- Peppol is the network. The GOV.UK Tax update 2026 summary says: "The government has announced that the electronic procurement system Peppol will be the core interoperability network for e-invoicing in the UK." The same document says the government will keep engaging on "the role of legacy systems which cannot interoperate in the future system".
- No real-time reporting to HMRC alongside the mandate.

**Not yet confirmed:** the final data standard. The consultation response says the government will review "the risks and benefits of adopting an existing standard or designing a UK-specific standard". Today's reference point is [Peppol BIS Billing 3.0](https://einvoices.uk/news/peppol-bis-billing-3-uk-guide), built on [EN 16931](https://einvoices.uk/news/en-16931-explained). Any UK-specific rules (a [CIUS](https://einvoices.uk/glossary#cius)) would affect your mappings. The roadmap is due at Budget 2026 on 28 October 2026.

## Three ways to connect an ERP to Peppol

| Option | How it works | Suits | Watch out for |
|---|---|---|---|
| **Native ERP feature** | The ERP's own e-invoicing or e-document module creates and sends documents, sometimes via a supplier-run or partner service | Businesses on current versions of the ERP | Licence cost, UK coverage, version upgrades required |
| **Add-on or partner connector** | A certified add-on maps ERP data to Peppol and connects to an Access Point | Older versions, or where native UK support is not ready | Support model, upgrade compatibility |
| **Separate Access Point or integration platform** | The ERP exports invoice data (via API or file); a provider converts, validates and sends | Several ERPs, billing systems or countries | Mapping ownership, two-way status flow, data duplication |

Many groups end up with a mix: the main ERP connected one way, and smaller billing systems another. A single Peppol connection for the whole group, fed from several systems, can be simpler to run.

## Questions to put to your ERP supplier or partner

Ask in writing and ask for the documentation reference:

1. For **our exact product, edition and version**, is UK Peppol sending supported today? Receiving?
2. Are invoices **and** credit notes supported, including self-billed invoices if we use them?
3. Is a version upgrade or new licence required?
4. Which Access Point is used? Is it on the [OpenPeppol list of certified service providers](https://peppol.org/members/peppol-certified-service-providers/)?
5. How will you implement UK-specific rules once the specification is published, and how quickly?
6. How are Peppol validation errors shown, and to whom?
7. Can incoming e-invoices be matched to purchase orders and goods receipts automatically?
8. Are Peppol [invoice responses](https://einvoices.uk/news/peppol-invoice-response-message-level-response) supported in both directions?
9. How are attachments stored and archived with the invoice?
10. Is there a test environment, and can we test with real trading partners?

Our [guide to checking Peppol support](https://einvoices.uk/news/check-accounting-software-peppol-support) explains how to judge the answers.

## ERP data mapping: where projects slip

ERP projects rarely fail on the connection; they slip on data. Map each [Peppol BIS Billing 3.0](https://einvoices.uk/news/peppol-bis-billing-3-uk-guide) field to an ERP source early:

- **Parties:** legal entity name, address, VAT number and [Peppol ID](https://einvoices.uk/news/peppol-participant-id-uk) for every company code or business unit.
- **Tax:** each ERP tax code to a [VAT category code](https://einvoices.uk/news/uk-vat-category-codes-peppol) and rate, including reverse charge and exempt codes.
- **References:** PO number and buyer reference ([BT-10](https://einvoices.uk/news/purchase-order-reference-buyer-reference-peppol)), contract and delivery references.
- **Units of measure:** ERP units to the code lists Peppol uses.
- **Rounding:** line and document totals calculated the way Peppol rules expect. Rounding is behind errors such as [BR-CO-15](https://einvoices.uk/news/peppol-validation-error-br-co-15).
- **Currency:** foreign currency invoices still need VAT totals in sterling under HMRC rules. See [multi-currency e-invoices](https://einvoices.uk/news/multi-currency-e-invoices-gbp).

## A suggested phased plan for ERP users

| Phase | Activities |
|---|---|
| 1. Discovery (now) | Inventory invoicing systems and volumes; ask suppliers the questions above |
| 2. Design | Choose connection option; map data; design exception handling |
| 3. Wait for spec | Confirm UK rules from the roadmap and guidance; adjust mappings |
| 4. Build and test | Configure, integrate, test with partners already on Peppol |
| 5. Pilot | Go live with a subset of customers and suppliers |
| 6. Roll-out | Extend to all in-scope entities before April 2029 |

Phases 1 and 2 can start now. See the full [e-invoicing project plan](https://einvoices.uk/news/e-invoicing-project-plan-finance-teams).

## Legacy systems

If part of your estate cannot produce structured invoices, raise it now. The government has said it will continue to engage on legacy systems that cannot interoperate in the future system, but has not said what any accommodation would be. Plan on the basis that you will need to replace or wrap them.

## What to do now

- [ ] List every system that creates VAT invoices, by legal entity.
- [ ] Send the ten questions above to your ERP supplier or partner.
- [ ] Start the tax code and party data mapping.
- [ ] Budget for licences, integration, testing and partner onboarding (see [e-invoicing costs](https://einvoices.uk/news/e-invoicing-cost-uk)).
- [ ] Work through the [readiness checklist](https://einvoices.uk/news/uk-e-invoicing-readiness-checklist).

## Frequently asked questions

### Does my ERP support Peppol e-invoicing in the UK?

Ask your ERP supplier or implementation partner for written confirmation for UK Peppol sending and receiving on your exact product and version. Capabilities differ between ERP editions, versions and add-ons, and the UK data standard is not yet final.

### Do we need middleware to connect an ERP to Peppol?

Not always. Options include a native e-invoicing feature, a supplier or partner add-on, or a separate Access Point or integration platform. The right choice depends on your ERP version, number of systems and countries.

### When should ERP users start their e-invoicing project?

ERP changes usually need testing and release cycles, so large businesses should start planning now, before the mandate in April 2029. Technical build can be finalised once the UK specification is published.

### Will the UK use Peppol BIS Billing 3.0?

Peppol is confirmed as the network, but the government has said it will review whether to adopt an existing standard or design a UK-specific one. Expect detail in the Budget 2026 roadmap.

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How to cite: "E-invoicing with an ERP system: what to ask and how to plan", einvoices.uk, 21 October 2026, https://einvoices.uk/news/e-invoicing-erp-systems-uk

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.