Firms and client portfolios

Accountants: getting your client portfolio ready for e-invoicing

The 2026 reform is not declared firm by firm: it is declared client by client. Each of your files has had to appoint an approved platform since 1 September 2026, and you are the first person asked about it.

Updated October 12, 2026 - Written by Diamontis FX

What changes in your practice

Collecting documents stops being a chasing exercise. Your clients supplier invoices arrive structured, dated and tied to their issuer: what used to require data entry or character recognition becomes usable data on arrival.

In return, a file that still has not appointed a platform stops receiving anything from its best-equipped suppliers. The subject is therefore not compliance in the abstract, but the continuity of your clients business.

Managing several companies from a single account

Diamontis FX is multi-company by design, not by an option bolted on afterwards:

• One account, several companies: you switch between them without logging out, each keeping its own tax settings and its own connection.
• Strictly partitioned data: the invoices of one file are never visible from another, and this isolation is enforced at two levels, application and database.
• Named access: every member of the firm has their own account with their own rights, and a revocation takes effect immediately.
• A portfolio: the list of your files, with a search and, for each one, the received invoices the manager has not yet viewed, the issued invoices overdue and unpaid, and the date of the last FEC produced.

Where to start with a portfolio

A portfolio is connected client by client. An order that works:

1. List the clients that have not yet designated a platform: equipped suppliers can no longer reach them.
2. Connect first the clients that receive the most supplier invoices.
3. Have the mandate signed by each company's manager, or by a person they have authorised: it is the company's consent that designates the platform.
4. Ask for access: from their own space, each client invites your address, and the file joins your portfolio as soon as you activate the invitation. The client keeps control of their invoices and can withdraw access at any time.

Retrieving entries: FEC export

The Fichier des Ecritures Comptables is the standard format the French tax authority requires during an audit. Diamontis FX exports it for the period of your choice, from invoices actually transmitted - not from re-keyed data. Entries are numbered and frozen at the first export, fiscal years are declared and closed, VAT on services follows payment and foreign-currency invoices are converted at the ECB rate.

It is also the easiest format to load into accounting production software: you do not have to change tools to work with an equipped client.

Evidential archiving, taken care of

Every invoice received is sealed and kept for ten years, with its fingerprint and its timestamp; invoices issued are kept by the approved platform that transmitted them. Your clients have nothing to organize on their side, and you get a reliable audit trail without having to reconstruct anything.

Which plan for a firm

Accountant access is open on every plan, Free included: each client invites you from their own space, and you have no company to declare and no plan to subscribe to in order to find their files in your portfolio. From the Pro plan, your client has the chart of accounts and Smart Comptable, which you can keep for them; the Business plan (€29 excl. VAT per month) adds Smart Analyse and brings up to three companies together on one account. For a large portfolio, a dedicated offer is discussed case by case, because it depends on the number of files and the pace at which they are connected.

Compare plans and their quotas

Official sources

This guide summarises public texts. When in doubt, they are what counts:

• Switching to e-invoicing (impots.gouv.fr, in French)
• E-invoicing and approved platforms (impots.gouv.fr, in French)
• The list of approved platforms (impots.gouv.fr, in French)

Legal basis: article 289 bis of the French General Tax Code, and article 91 of French Finance Act no. 2023-1322 of 29 December 2023 for 2024, which sets the timetable.

Going further

• The 2026 reform: obligations and timetable
• E-reporting: what your clients will have to file
• Frequently asked questions from firms