How to replace an ERP without losing tax-reporting history
Make historical reporting part of the migration scope before you switch off the old system. Opening balances and a folder of PDFs may be insufficient to reproduce an audit file or explain a transaction's reporting history.
Start with the records the business must retain and the outputs it may need to reproduce. Then decide which information belongs in the new ERP, a controlled archive or a retained reporting environment.
This guide describes a migration method. Retention periods, permitted formats and authority access depend on the jurisdiction and record category.
Diagram: Inventory, preserve, rehearse, reconcile and retire. Recommended cutover sequence. National retention rules and open audits determine the retained scope.
Define the retained record set
Inventory ledgers, invoices, credits, attachments, payment allocations, tax mappings, master-data history, submission files and acknowledgements. Include account mappings and reporting adjustments maintained outside the ERP.
For each set, record its owner, legal entity, period, location, format, retention rule and retrieval method. Identify legal holds or open audits before scheduling deletion.
Use a country-specific retention decision. UK guidance for limited-company accounting records gives six years from the end of the relevant financial year, with conditions requiring longer retention. GOV.UK, company and accounting records
France's official business guidance gives ten years from financial-year close for accounting books and supporting documents. Other document categories can follow different rules. Service Public Entreprendre, document retention
Those examples establish why a global default needs review. They do not establish retention rules for every record in either country.
Preserve relationships as well as files
Keep stable identifiers linking a source document, ledger entry, correction, payment and external response. Record the source system and original identifier when the new ERP assigns a different one.
Preserve the local account and tax mappings used for historical periods. An old document interpreted through today's master data can produce a different result. Keep the effective dates and configuration needed to explain the original treatment.
Store readable exports and the structured originals required by the selected retention plan. Verify that attachments remain linked and that an operator can find them without access to a former employee's account.
Choose the historical operating model
Decide whether the new system will reproduce old reports, the old system will remain available in a controlled mode or a dedicated archive will supply the evidence. Test the chosen approach before termination dates make another choice expensive.
Document the costs and dependencies. An archive can still need licenses, encryption keys, report software and trained users. A retained ERP can still need maintenance and supported access controls.
Assign an owner for historical requests. Record how an accountant or authority request reaches that owner and what approval is needed to disclose records.
Rehearse an actual retrieval request
Choose a closed period and produce a representative audit or tax output. Trace selected transactions to their supporting documents and responses. Ask a person outside the migration team to follow the retrieval instructions.
Check the output against the retained ledger and original filing evidence. Record intended differences, such as a corrected report. Use the validator appropriate to the historical format where one is available.
DGFiP publishes standards and schema information for accounting files provided in a tax-audit context. Use the relevant specification when testing a retained French FEC process. DGFiP, standard accounting files
Control the cutover boundary
Identify the final source-system transaction and first target-system transaction for each population. Decide which system owns documents in flight, corrections to earlier invoices and submissions awaiting acknowledgement.
Reconcile opening balances and migrated open items to the signed-off source. Reconcile the document population separately. A balanced ledger can still omit an attachment, external identifier or pending submission.
Prevent both systems from submitting the same backlog. Define how late responses are collected and linked after cutover. Test a correction to a pre-cutover document in the agreed operating model.
Balance retention and data protection
Separate statutory retention, business convenience and unnecessary copies. Apply access controls and deletion rules to each category.
GDPR guidance explains that a legal retention obligation can affect an erasure request. Have the privacy owner decide which records must remain and how access is restricted. Do not apply a blanket customer-deletion process to retained accounting evidence. Your Europe, data protection under GDPR
Include archive providers in the access and exit review. Record who can export data, how keys remain available and what happens when the provider contract ends.
Authorize retirement only after evidence is accepted
Require finance to accept balances and historical reporting. Require operations to demonstrate retrieval and the handling of in-flight documents. Require the records owner to accept retention and deletion decisions.
Keep the migration mappings, extraction logs, reconciliation, sample retrieval and approval record together. Resolve failed retrievals before retiring the environment that can still answer them.
Schedule a later retrieval rehearsal under the records-management routine. Staff, credentials and service contracts change after a project closes. The evidence is useful only while the business can still retrieve and explain it.
Related on this site
- Country pages: key facts with sources
- E-invoicing matrix: country × ERP support
- All guides
Vendor documentation is cited only as an example of the level of evidence to ask for; it is not a recommendation or a ranking. This guide is general information, not tax or legal advice. Checked 2026-10-17.
Related: Glossary – abbreviations and terms used in these guides (SAF-T, Peppol, CTC, EN 16931, IFRS and more).
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