Changing your accounting software: a successful migration and change management

Quick answer. To change accounting software, a migration succeeds when you scope the need, pick a tool compatible with electronic invoicing, switch over at a closing date and secure the accounting entries file beforehand. Electronic invoice reception becomes mandatory for all businesses on 1 September 2026. Plan for a parallel-control period and a final review by your chartered accountant.

Many businesses do not switch tools for comfort, but because a deadline forces them to. The roll-out of mandatory electronic invoicing is that trigger. On 1 September 2026, every business must be able to receive an electronic invoice. On the same date, large enterprises and mid-caps (ETI) must also issue their invoices electronically; small and medium-sized businesses (SMEs and very small businesses) follow on 1 September 2027.

In practice, your software must be able to communicate with an accredited platform, connected to the public directory and portal. A tool that can neither issue nor receive these flows will become a bottleneck. This is why the questions of changing accounting software and of migration arise together, and not only as a technical matter: it is also change management for your teams.

For the overall framework of the reform, see our 2026 electronic invoicing guide for SMEs, and the detailed workings of accredited platforms and the reliable audit trail.

The date that concerns everyone as early as 2026 is reception. Even a very small business that does not yet issue electronically must be able to receive supplier invoices. This point often drives a change of tool, or at least its connection to a platform. To check whether your invoicing tool is compliant, see our note on the invoicing software required in 2026.

An accounting migration is not an export followed by an import. It is an ordered procedure, where each step conditions the next. Here is the method we apply in tool-change engagements.

1. Scope the real need and the 2026 constraints. List your volumes, journals, VAT regimes, cost-accounting axes, bank interfaces and electronic invoicing obligations. You should not pick a tool before writing down what you genuinely need.
2. Pick a tool compatible with electronic invoicing. Check the ability to issue and receive through an accredited platform, history migration and FEC export. A modern, connected tool also supports your data-driven management.
3. Plan the switch at a closing date. A mid-year switch multiplies the risk of breaks. Year-end, or at least the end of a closed quarter, gives a clean restart point: locked balances, declared VAT, reconciled accounts.
4. Export and secure the FEC and the history. Generate the accounting entries file (FEC), keep the balances, third-party accounts and outstanding items, and check data integrity before any switch. Document archiving and the reliable audit trail must be preserved.
5. Configure and migrate the data. Set up the chart of accounts, VAT rates and codes, document numbering, then migrate balances, third parties and outstanding items. Loose VAT configuration is expensive at the next return.
6. Train the teams and support the change. Identify who records what, who validates, who reconciles. Training and human support make the difference between an adopted tool and an endured one.
7. Run a parallel control and validate with your chartered accountant. Run a period of dual entry or parallel control, reconcile the balances of the old and new tools, and have your chartered accountant validate the configuration and the migration.
8. Archive and document. Keep the history of the old system, document the account and numbering mappings, and keep a written record of the configuration choices.

These eight steps are not interchangeable. The most common mistake is to swap steps 3 and 4, that is, to switch over before securing a clean FEC.

The quality of the migration comes down to a few precise points. The table below maps what must be migrated against the risk if the point is neglected.

The risks of a failed migration are concrete: data losses, numbering breaks, entries not migrated, double recording, incorrect VAT configuration, loss of history. Each can be fixed, but far more easily before the switch than after.

Our reading. A migration rarely fails on technology alone. It fails when teams have not been brought on board: cautious duplicate entries, rejection of the new tool, an unofficial return to the old spreadsheet. Change management means explaining why you are switching, training people, and appointing an internal reference. If you are structuring an internal accounting function, our article on managing an internal accounting team extends this point.

That said, change management must not turn into abstract management. The goal stays accounting: producing correct accounts, in a controlled tool, in time for the returns. The human side serves that goal; it does not replace it.

Not every situation is handled the same way.

• Very small businesses and micro-enterprises without full bookkeeping. The 2026 issue is mainly receiving invoices. An invoicing tool connected to a platform may be enough, without a heavy accounting migration.
• A growing business with cost accounting. Migrating analytical axes and multi-year history requires finer scoping. It is better to switch at the annual closing.
• A group or holding company. Configuration consistency across entities and consolidation call for a coordinated, item-by-item migration. The role of the chartered accountant is central here.
• A business changing both tool and management approach. Some teams run part of their management in lightweight tools. Our comparison of Notion versus Coda for internal accounting management helps separate the statutory accounting tool from a simple management dashboard.

The underestimated risk. The most frequent trap is not the switch itself, but the period between two closings. Switching mid-year without a clean FEC migration lets through discrepancies that only surface at the next closing.

Recently, an SME came to us after changing tools mid-year, without a clean migration of the accounting entries file. The opening balances had been re-keyed by hand, with no reconciliation against the old balance. The result: balance discrepancies that we had to identify and correct urgently at closing, under tight deadlines. A switch planned at the closing date, with a secured FEC, would have avoided this corrective work.

In practice, three reflexes limit this risk:

• Never re-key opening balances by hand without reconciliation against the old system's balance.
• Keep the old tool accessible in read-only mode for at least one financial year.
• Validate the VAT configuration and numbering before the first real return.

The right moment to change accounting software is not "when the old tool becomes annoying", but when a deadline justifies it and a closing date allows a clean migration. The 2026 constraint is a good opportunity to do it under good conditions, provided you do not wait until summer to start.

At Hayot Expertise, as chartered accountants registered with the Ordre, we validate the configuration and the migration to secure what truly matters: the integrity of the FEC, the consistency of the balances, VAT compliance and the continuity of the reliable audit trail. The choice of tool is yours; our role is to make sure the migration does not create hidden accounting debt. For day-to-day bookkeeping and review, see our bookkeeping and accounting review service in Paris; for the tax side, our business taxation support; and for the contractual aspects of changing provider or tool, our legal advice.