Definition
A letter arrives from Urssaf. It asks for no money: it announces that an officer will review your situation, and lists the documents to get ready.
The reaction is always the same, a knot in the stomach and the certainty that something somewhere was done wrong.
Most of the time nothing serious has happened: your file came out of a data cross-check, or one declaration looked odd next to the money paid into your account.
An URSSAF audit is the review, by URSSAF, the body that collects social contributions, of what you owe it as a self-employed worker.
It covers one thing only: the link between the money actually received in your account and the Social contributions declared on it. It judges neither the quality of your work, nor your profitability, nor your income tax, which belongs to a different administration.
What the officer really looks at
Three points, always the same ones. The amount first: your bank statements are compared line by line with your Income ledger and your Turnover declaration.
Then the category, sale of goods, craft or commercial services, liberal activity, because each one carries a different rate.
Then the reliefs, ACRE above all, where the officer checks that the conditions were met on the start date of the activity and that the reduced-rate period stopped when it was due to stop.
A worked example: the box ticked too fast
Take a freelance developer, in a non-regulated liberal activity attached to the general scheme. In 2026 he collects 30,000 euros.
When registering, he ticked sale of goods instead of other services, and has been declaring at the sale-of-goods rate ever since, 12.3% in 2026, so 3,690 euros of contributions for the year.
The rate that applies to his activity is 25.6% in 2026, so 7,680 euros.
The 3,990 euro gap comes from no hidden euro, it comes from a box. On top of that sits the CFP, the contribution à la formation professionnelle or vocational training contribution.
It is owed as soon as revenue was declared in the previous calendar year, at 0.2% for a liberal profession in 2026, so 60 euros. The headline rate never covers everything owed to Urssaf.
And be wary of borrowing someone else's rate, an architect attached to the Cipav pension fund being at 23.2% that same year.
The audit starts from your bank account, not from your invoices. In a micro-enterprise only the date of Cash receipt counts: a December invoice paid in January belongs to the following year, and an invoice never paid is never declared at all.
Two consequences that officers pick up often. Commission withheld by a platform cannot be subtracted from the revenue you declare, even when the transfer you receive is the net amount.
And a quarter with no income still has to be declared, at 0 euros: a missing declaration stands out far more than a small figure.
Urssaf audit and tax audit: different officers
Confusing the two wastes time and produces the wrong paperwork.
Urssaf collects social contributions, the CFP and the chamber levies, all calculated as a percentage of the revenue you declare.
The tax administration handles income tax, VAT and the CFE (cotisation foncière des entreprises, the business property tax).
A service provider who crosses the VAT exemption threshold, set for services at 37,500 euros of previous-year revenue in 2026, must charge VAT without a single cent of change to their contributions: that crossing is no business of Urssaf.
That figure is a sub-threshold, not a stand-alone one: total revenue, sales included, must also stay under 85,000 euros in 2026.
The micro-scheme ceiling is a different figure and a different subject, 83,600 euros for the same activity in 2026, and it concerns both administrations.
One last boundary worth knowing: an audit that ends in Reclassification as employment almost always starts at the client, not at the contractor.
How it unfolds
For micro-entrepreneurs, most audits are handled on documents alone: a request for paperwork, processed remotely, with no officer visiting.
An on-site audit is announced by a notice sent in advance, together with the charte du cotisant contrôlé (the audited contributor's charter) setting out your rights; only investigations into undeclared work skip that advance notice.
Everything ends with a lettre d'observations (the findings letter), where each adjustment is quantified and explained, and which you may answer in writing within the deadline it states.
Nothing is collected before you have had the chance to reply. Only then, if the disagreement stands, come the mise en demeure (formal demand) and the appeal routes, starting with the commission de recours amiable (the internal appeals board).
Late-payment surcharges are added to the sums claimed, which makes silence expensive; the full procedure is published by Urssaf.
Frequently asked questions
Can a micro-entrepreneur really be audited?
Yes. The scheme simplifies how contributions are calculated, it does not remove the checking.
The audit is even quicker than elsewhere, since there are no accounts to comb through: a few bank statements, the income ledger and the declaration history are enough to cross-check most of the file.
How far back can an adjustment go?
Over the periods that are not yet time-barred, a duration set by the social security code and restated in the notice you receive.
That is precisely why record-keeping rules exist: keep bank statements, invoices and your income ledger for the whole required period, including after you deregister your business.
I disagree with the findings letter, what can I do?
Reply in writing within the stated deadline, point by point, attaching the documents missing from the officer's file rather than arguing the principle.
Many adjustments collapse at this stage, simply because a proof of payment or a certificate of affiliation had never been sent in.
What if I cannot pay what is being claimed?
Write before the due date to ask for a payment plan, rather than letting the debt run.
One point that is often missed: your pension rights are calculated on the contributions actually paid, never on those merely owed.
Getting compliant therefore does more than avoid surcharges, it also recovers pension quarters. Situation up to date as of 5 September 2026.