What Microsoft has said
Microsoft's roadmap entry (ID 573621) is listed as "In development". It targets preview in November 2026 and general availability in February 2027 for the Worldwide (Standard Multi-Tenant) cloud, on the Web platform. These are roadmap estimates, and Microsoft says roadmap information is subject to change.
The roadmap description makes four points:
- The French localization is delivered as a set of extensions on the W1 base app.
- A data upgrade feature is meant to ease the move from the previous localization.
- The release is a step toward full delocalization, so ISVs can reach a wider market.
- Some features move into the base app or become global apps, and others stay France-specific.
Microsoft Learn's France local functionality page, last updated October 8, 2026, says that in 2026 release wave 2 (v29), the French version of Business Central becomes a set of extensions on top of the W1 Base App. It adds that for the next three releases, you can choose whether to enable the new features. After that period, Microsoft will deprecate the previous features and automatically enable the extension.
In practice, that means an opt-in window followed by a forced cutover. The Learn page also lists "Delocalization of FR base app" as planned during 2026.
What is not yet public
I found no public documentation that covers any of the following:
- The upgrade procedure, prerequisites and supported source versions.
- Whether the data upgrade is automatic or administrator-initiated.
- Rollback options.
- The exact versions that make up the three-release window.
- A feature-by-feature list of what moves to the base app, becomes a global app, or stays French-only.
Treat the data upgrade as a roadmap-stated capability, not a verified migration workflow. I also won't give installation steps, because none are documented in the material I found.
The UK precedent
The UK localization went through the same transition. The English-language blog series from azurecurve describes the UK localization as a set of extensions on the W1 base app, with a data upgrade to ease the transition from the previous localization. That wording closely matches the French roadmap text.
Microsoft's country/region availability page says the UK BaseApp was migrated to W1 with Business Central 2025 release wave 2. Current localization features are available as apps, and users can enable new features through Feature Management. The same page says Sweden's BaseApp was migrated to W1 with 2023 release wave 1.
I haven't confirmed that France will use the same mechanism. The UK path is a reasonable guide to what to expect, not a promise.
What the French extensions cover
Microsoft's France page lists these features as "Available Now":
- VAT and tax: audit export, general ledger export to XML, and declarations of trade in goods and services (DES).
- E-invoicing: French e-reporting and electronic invoicing with UBL 2.1 and Factur-X.
- Banking and payments: payment addresses, statuses, steps and classes; creating, archiving and posting payment slips; payment management; and exporting or importing setup parameters.
- Core finance: fiscal periods and years, closing and reopening of periods, year-end entries, general ledger reports, and ledger reconciliation views.
- Sales: invoices with French-specific details.
- Fixed assets: accelerated depreciation.
The page does not say how each item is affected by the move. "Available Now" describes availability of French functionality, not which pieces are changing.
Who should care
- French tenants and finance teams: Fiscal closing, payment slips and e-invoicing are exactly where a localization change can cause trouble. Plan regression testing before enabling the extensions in production.
- Implementation partners: Look for guidance on how per-tenant extensions and customizations interact with the new structure. This is general industry reasoning, not something Microsoft has documented for France.
- ISVs: Delocalization is meant to let one app reach more markets. The sources don't say that French features become usable elsewhere, or that apps will run unchanged across countries.
Suggested preparation
- Note which v29 release your environments will reach, and when the preview becomes available.
- Inventory customizations and apps that touch French localization objects.
- Test in a sandbox first. Cover fiscal closing, payment slips, Factur-X invoicing and accelerated depreciation.
- Use Feature Management as the likely control point only if Microsoft's v29 documentation confirms it for France. Today that is inferred from the UK precedent.
- Don't treat the opt-in window as indefinite. The extension will eventually be enabled automatically.
Dates may move, and the migration details are still thin. The three-release opt-in window gives French customers time, but only if they use it for testing.