Project plan for the switch to e-invoicing
Since 2025, companies in Germany must be able to receive e-invoices; the obligation to send them follows step by step in 2027 and 2028. The switch affects accounting, purchasing, ERP and archiving at once. This plan shows it for a wholesaler with 70 employees, from XRechnung and ZUGFeRD to audit-proof archiving.
No sign-up · opens instantly · 16 Weeks · 7 Phases · 39 Tasks · Budget approx. €58,500
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Electronic Invoicing and ERP/Accounting Integration
The project will introduce electronic invoice receipt and transmission using XRechnung and ZUGFeRD. It will integrate invoice processing with the existing ERP and accounting systems, including validation, approval, posting, reconciliation, and exception handling. Invoices and related evidence will be retained in an audit-proof archive that meets German GoBD requirements. GDPR requirements, including the Art. 28 data processing agreement and the Art. 30/35 assessments, will be completed before applicable processing and go-live activities, while accounting users will receive role-specific training.
Phases
Phase 1: Initiation and Current-State Assessment
Establish project governance and document the current invoice, ERP, accounting, and archiving landscape. This creates the baseline for scope, volume estimates, compliance planning, and the four-month delivery schedule.
Phase 2: Requirements, Compliance and Provider Readiness
Finalize business, technical, tax, GoBD, and privacy requirements and confirm that the selected provider can support the required formats and controls. The GDPR Art. 28 DPA, Art. 30 RoPA update, and Art. 35 DPIA screening are established as formal compliance work items and go-live gates.
Phase 3: Target Process and Technical Design
Define the future-state invoice lifecycle and technical design for receiving and sending XRechnung and ZUGFeRD invoices. The phase also specifies the controls and evidence needed to demonstrate completeness, traceability, and auditability under GoBD.
Phase 4: ERP, Accounting and E-Invoicing Integration
Configure the ERP, accounting, e-invoicing, and transmission components and build the required interfaces and controls. The provider DPA must be executed no later than Week 10 and before any testing or migration involving real personal or invoice data.
Phase 5: GoBD Archive Setup and End-to-End Testing
Implement the audit-proof archive and verify complete invoice lifecycles from receipt or creation through validation, approval, posting, transmission, retention, and retrieval. Testing uses approved representative data now that the provider DPA is in place.
Phase 6: User Acceptance, GDPR Finalization and Training
Confirm business acceptance, complete the required GDPR documentation, and prepare accounting users for the changed invoice processes. The RoPA update and Art. 35 DPIA necessity decision are completed two to four weeks before the planned Week 16 cutover.
Phase 7: Go-Live and Hypercare
Execute the controlled production cutover, monitor invoice transmission and accounting postings, and stabilize the solution during hypercare. Operational and audit readiness are verified before project closure at the end of Week 16.
Timeline
Budget
| Item | Qty | Unit price | Total |
|---|---|---|---|
| Integration architect: interface and posting design | 5 Person days | €1,100 | €5,500 |
| ERP integration developer: APIs, mappings and transmission workflows | 10 Person days | €900 | €9,000 |
| Posting logic, approval workflow and error-handling configuration | 2 Person days | €875 | €1,750 |
| Item | Qty | Unit price | Total |
|---|---|---|---|
| E-invoicing module activation and tenant setup | 1 Flat rate | €7,000 | €7,000 |
| XRechnung and ZUGFeRD format handling and validation package | 1 Flat rate | €2,500 | €2,500 |
| E-invoice transaction capacity and service subscription | 4 Person days | €550 | €2,200 |
| Item | Qty | Unit price | Total |
|---|---|---|---|
| GoBD archive configuration, retention rules and immutability setup | 1 Flat rate | €6,000 | €6,000 |
| Audit trail, access control and retrieval validation | 2 Person days | €1,100 | €2,200 |
| GoBD procedural documentation and audit evidence package | 3 Person days | €950 | €2,850 |
| Item | Qty | Unit price | Total |
|---|---|---|---|
| IT/ERP administrator: master-data and tax-field cleansing | 5 Person days | €600 | €3,000 |
| AP/AR key users: approved test datasets and business scenarios | 6 Person days | €350 | €2,100 |
| Migration and reconciliation consultant: archive and accounting reconciliation | 2 Person days | €900 | €1,800 |
| End-to-end defect retesting and test evidence pack | 1 Flat rate | €900 | €900 |
| Item | Qty | Unit price | Total |
|---|---|---|---|
| Accounting training workshops for AP, AR and accounting staff | 16 Person days | €180 | €2,880 |
| Operating instructions, exception procedures and user support materials | 2 Person days | €835 | €1,670 |
| Production cutover and go-live support | 2 Person days | €1,000 | €2,000 |
| Post-go-live monitoring, incident triage and stabilization support | 1 Flat rate | €1,250 | €1,250 |
| Item | Qty | Unit price | Total |
|---|---|---|---|
| GDPR Art. 28 DPA review, provider negotiation and execution before real-data testing or migration (Phase 2) | 15 Person days | €1,000 | €1,500 |
| GDPR Art. 30 record of processing activities update (initial review in Phase 2, finalization in Phase 6) | 1 Flat rate | €900 | €900 |
| GDPR Art. 35 DPIA necessity assessment and documented decision (initial review in Phase 2, finalization in Phase 6) | 1 Flat rate | €900 | €900 |
| Tax adviser validation of mandatory invoice fields, tax coding and format requirements | 75 Person days | €800 | €600 |
Risks
Incorrect Tax Data or Mandatory Invoice Fields
If ERP mappings for VAT codes, buyer identifiers, invoice references, totals, payment terms, or other mandatory fields are incomplete by the design sign-off in Week 6, XRechnung or ZUGFeRD invoices may be rejected, posted incorrectly, or create tax and audit findings during Weeks 10–16.
GDPR Article 28 DPA Not Executed Before Real-Data Processing
If the provider’s data processing agreement is not signed before any real invoice data is used for testing, migration, or production preparation, processing may begin without the required GDPR Art. 28 contract.
Incomplete RoPA Update or DPIA Necessity Assessment
If the new provider, invoice data flows, retention activities, access roles, or transfer arrangements are not documented by Week 12, the project could reach go-live without a complete GDPR Art. 30 record or a documented Art. 35 DPIA decision.
GoBD Archive Is Not Audit-Proof
If the archive cannot demonstrate immutability, completeness, traceability, retention, access history, original-format preservation, or timely retrieval during testing in Week 12, invoices may not be sufficiently verifiable during a German tax audit.
ERP, Accounting, and Invoice Reconciliation Errors
If interface mappings, master data, posting rules, approval workflows, or retry handling are defective after integration work in Weeks 7–10, invoices may be duplicated, omitted, misposted, or approved without adequate controls.
Partner Interoperability or User Adoption Failure
If key customers or suppliers cannot process the selected XRechnung or ZUGFeRD profile by Week 12, or accounting users are not trained and UAT is incomplete by Week 14, manual workarounds may delay payments, weaken controls, and disrupt month-end closing after go-live.
Stakeholders
Managing Director or Executive Sponsor
Owns the business case and budget, resolves scope escalations, and grants final go-live approval.
Head of Accounting
Defines posting, reconciliation, approval, exception-handling, and month-end requirements and accepts the accounting solution.
Accounts Payable and Accounts Receivable Representatives
Validate incoming and outgoing invoice workflows, usability, partner scenarios, and operational exception handling.
IT/ERP Administrator
Owns environments, configuration, interfaces, access rights, backups, deployment, monitoring, and technical cutover.
Tax and Compliance Lead or External Tax Adviser
Confirms mandatory invoice content, tax coding, format compliance, retention rules, and audit evidence.
Data Protection Officer or Privacy Counsel
Reviews data flows, approves the Art. 28 DPA, updates the Art. 30 record, and documents the Art. 35 DPIA necessity decision.
E-Invoicing and Archive Provider
Provides XRechnung/ZUGFeRD processing, transmission, archive controls, service documentation, and contractual privacy commitments.
ERP Integration Partner or Implementation Consultant
Designs and delivers interfaces, mappings, posting logic, test support, migration activities, and defect remediation.
Compliance
Execute a GDPR Art. 28 data processing agreement with the e-invoicing/archive provider before any processing of real invoice data, including real-data testing or migration.
Update the GDPR Art. 30 record of processing activities to document invoice data categories, purposes, recipients, systems, provider processing, retention, access roles, and data flows.
Assess whether a GDPR Art. 35 data protection impact assessment is required for the new processing, document the necessity decision, and complete a DPIA if the assessment identifies high risk.
Implement GDPR-appropriate security and access controls, including role-based access, least privilege, authentication, logging, backup protection, and controlled administrator access for ERP and archive systems.
Support and validate the required XRechnung and ZUGFeRD profiles, including EN 16931-relevant structured data, metadata, attachments, validation results, and customer or supplier interoperability.
Configure and document GoBD-compliant retention and archiving, including preservation of invoice content and original format, immutability, completeness, traceability, audit trails, retrieval, access controls, retention periods, and operating procedures.
Train accounting users on electronic invoice receipt and dispatch, validation, approvals, exception handling, archive retrieval, privacy controls, and month-end reconciliation, with attendance and operating instructions documented.
Milestones
- Week 2
Approved project charter and documented current-state assessment covering invoice processes, systems, interfaces, volumes, and archive requirements.
Depends on: Sponsor alignment and access to current process, system, interface, volume, and archive information - Week 4
Approved requirements and compliance register, completed initial GDPR assessment, and DPA package ready for execution.
Depends on: Approved charter, current-state assessment, provider participation, and privacy review - Week 6
Signed-off target process model, interface and mapping specification, format rules, GoBD control design, and test strategy.
Depends on: Approved requirements, compliance register, and confirmed provider capabilities - Week 10
Configured and unit-tested ERP/e-invoicing integration, validated master data, and executed Art. 28 DPA before any real-data testing or migration.
Depends on: Signed-off technical design, available environments, provider access, clean master data, and executed DPA before real-data use - Week 12
GoBD archive controls operational and documented, end-to-end test evidence complete, and all critical defects resolved or formally blocked from go-live.
Depends on: Completed integration, configured archive, approved test data, and successful unit testing - Week 14
UAT acceptance completed, RoPA and Art. 35 assessment finalized, accounting users trained, and formal readiness approval issued for Week 16 cutover.
Depends on: Successful end-to-end testing, resolved critical defects, completed privacy documentation, and trained users - Week 16
Production invoicing operational, reconciliations completed, no critical transmission or posting defects outstanding, and operational GoBD/GDPR evidence handed over.
Depends on: Formal readiness approval, completed cutover plan, production access, and operational support coverage
How this plan was created
This plan was created by PathHub AI from a single description: “Switch to electronic invoicing at a wholesale company with 70 employees: receiving and sending in XRechnung and ZUGFeRD format, ERP and accounting integration, audit-proof archiving under German GoBD rules, training for accounting. Completion in four months.” — without company context. With your departments, approval processes and compliance requirements it becomes much more precise.
Obligations with lead time: what many think of too late
These obligations are typically triggered by the switch to e-invoicing (example: Germany). PathHub AI schedules them with lead time, warns when the schedule is too tight and shows the rule with its criteria under “Rule & evidence”, which you tick off and back with evidence. Not legal advice.
Rule & evidence
Why: Invoices are tax-relevant; format and archiving change with the switch.
Legal basis: Since 1 Jan 2025 domestic businesses must be able to receive e-invoices; issuing obligation from 2027 above EUR 800,000 prior-year turnover, from 2028 generally for all (Sec. 14 UStG). Process documentation and archiving under GoBD.
- Process documentation for all tax-relevant systems and procedures
- Complete and unalterable records, changes are logged
- Retention of tax-relevant documents for the statutory period (generally 8 or 10 years)
- Data access for tax audits possible (Sec. 147(6) German Fiscal Code)
- Receipt of structured e-invoices (XRechnung, ZUGFeRD) since 1 Jan 2025
- Issuing e-invoices to domestic businesses: from 2027 for prior-year turnover above EUR 800,000, from 2028 generally for all (exceptions incl. small-amount invoices, small businesses)
If breached: Formal defects can lead to the bookkeeping being rejected and the tax base being estimated (Sec. 162 German Fiscal Code); refusing data access can trigger a delay penalty (Sec. 146(2c)).
Rule & evidence
Why: Invoices contain personal data of contacts and sole traders.
Applies: if an external service or portal processes invoice data
Legal basis: GDPR Art. 28: contract before processing starts.
- Data Processing Agreement (DPA) with cloud provider
- SLA with availability, RPO, RTO
- Exit and portability clause
- Data localisation and transfer mechanism (SCC / adequacy)
If breached: Civil claims for data loss; recourse depends on contract. GDPR fines for non-compliance.
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