E-invoicing implementation plan for UK finance teams

A good e-invoicing implementation plan has six phases: mobilise, discover, design, build, pilot and roll out, with five workstreams running through them: accounts receivable, accounts payable, master data, technology and trading partners. Start the first two phases now; the later ones depend on the UK specification, expected from the roadmap at Budget 2026 on 28 October 2026, ahead of the mandate on April 2029.

This plan is written for finance teams in mid-sized and larger UK businesses. Smaller businesses can use the readiness checklist instead.

Fixed points to plan around

Confirmed:

• Mandate for VAT invoices from April 2029 (consultation response).
• Peppol as the network: "The government has announced that the electronic procurement system Peppol will be the core interoperability network for e-invoicing in the UK" (GOV.UK Tax update 2026 summary, 23 June 2026).
• Decentralised model, no real-time reporting at launch.
• HMRC's 2026 transformation roadmap update says HMRC is working with the Department for Business and Trade "to publish an e-invoicing roadmap at Budget 2026 that will set out the milestones" to implementation in April 2029.

Not yet confirmed: interim milestones, the data standard, phasing by business size, penalties, provider accreditation. Build your plan with these as dependencies and revisit it after 28 October 2026.

Governance

Role	Typical owner	Responsibility
Sponsor	CFO or finance director	Budget, priority, decisions
Project lead	Financial controller or finance systems lead	Plan, risks, reporting
AR lead	Credit control / billing	Sales invoice process, customer readiness
AP lead	Purchase ledger	Supplier invoice intake, matching, approvals
Tax lead	VAT manager or adviser	VAT rules, scope, edge cases
Technology lead	IT / ERP team	Integration, Access Point, testing
Procurement lead	Procurement	Supplier onboarding and contracts

Hold a short monthly steering meeting from now, weekly once build begins.

Phase 1: Mobilise (start now)

• Appoint sponsor and leads.
• Agree scope: which legal entities, which invoice flows.
• Set up a risk log and decision log.
• Budget for discovery and vendor engagement (see what e-invoicing costs).

Phase 2: Discover

• Inventory every system that creates or receives invoices, by entity.
• Measure volumes: invoices and credit notes sent and received, by channel and partner.
• Identify edge cases: self-billing, VAT groups, reverse charge, foreign currency, Northern Ireland, Isle of Man.
• Ask software vendors for written Peppol plans (see checking software support and our ERP guide).
• Record a baseline of costs and cycle times, so you can measure benefits.
• Assess master data quality.

Output: a discovery report with systems map, volumes, gaps and options.

Phase 3: Design

• Choose the connection approach: native ERP feature, add-on, or a separate Access Point.
• Decide your Peppol identifiers for each entity.
• Map invoice data to Peppol BIS Billing 3.0 fields, flagging items to confirm against UK rules.
• Map tax codes to VAT category codes.
• Design exception handling: validation failures, delivery failures, customer rejections.
• Decide whether to send and process invoice responses.
• Design archiving to meet HMRC record-keeping rules (see archiving and retention).
• Segment trading partners for onboarding.

Dependency: the UK specification. If it is not published by the time you finish design, design against Peppol BIS Billing 3.0 and keep a list of assumptions.

Phase 4: Build and test

• Configure software and Access Point; register Peppol IDs.
• Build integrations and mappings.
• Unit test with sample invoices, including credit notes and edge cases.
• Run validation testing; fix the common errors.
• End-to-end test with friendly partners already on Peppol.
• Update procedures and train users.

Phase 5: Pilot

• Go live with a small group of customers and suppliers.
• Monitor rejection rates, delivery failures and processing time.
• Fix issues before scaling.

Phase 6: Roll out

• Onboard remaining partners in waves (see supplier onboarding).
• Retire old channels where possible, keeping fallbacks for out-of-scope documents.
• Hand over to business-as-usual owners with clear service levels.
• Complete well before April 2029.

Workstreams across the phases

Workstream	Key deliverables
Accounts receivable	Send process, customer IDs, exception handling (AR guide)
Accounts payable	Intake, matching, approvals, responses (AP guide)
Master data	Clean customer and supplier records, VAT numbers, Peppol IDs
Technology	Connection, integrations, testing, archive
Trading partners	Segmentation, communications, onboarding
Tax	Scope, edge cases, VAT invoice compliance, tracking HMRC guidance

Risk register starters

Risk	Mitigation
UK specification published late or differs from Peppol BIS Billing 3.0	Design for change; keep mappings configurable; contract for updates
Vendor not ready	Get dated written commitments; identify an alternative Access Point
Poor master data	Start clean-up in phase 2
Legacy systems cannot produce structured data	Replace, consolidate or route through an integration layer; track government engagement on legacy systems
Partners not ready	Segment and communicate early; keep a fallback channel
Resource clash with year-end or other projects	Plan phases around your finance calendar

What to do now

• Name a sponsor and a project lead this month.
• Start discovery: systems, volumes, vendors, data.
• Watch the Budget on 28 October 2026 and update the plan with any official milestones. We will update the timeline.