Side Business: Starting an Activity Alongside Your Job

Quick answer. An employee can start an activity alongside their job, most often as a micro-entreprise, provided they respect the duty of loyalty and any exclusivity clause. In 2026, the micro regime thresholds are EUR 203,100 (sale of goods) and EUR 83,600 (services and BNC activities). The real challenge is not administrative: it is time management and the timing of the switch.

Launching a side business has become a reflex for many employees: testing an idea, building a complementary income, preparing a career change without cutting the safety net of a salary. The difficulty is almost never the creation itself, which takes minutes online. It lies elsewhere: choosing a status that does not cost more than it earns, watching the right thresholds, staying loyal to your employer, and recognising the moment when the secondary activity deserves to become the main one.

This article is aimed at private-sector employees and public agents who want to structure a parallel activity without taking needless risks. We set out the trade-offs we see recurring in start-up files, with figures up to date for 2026 and the blind spots that prove costly when discovered too late.

In the private sector, the principle is freedom: nothing prevents an employee from carrying out a self-employed activity outside their working hours. Two limits frame that freedom.

• The duty of loyalty. It applies even without a written clause. You cannot compete with your employer, divert their clients, or use their resources (equipment, files, working time) for your personal activity.
• The exclusivity clause. If your contract contains one, it may prohibit any other professional activity. Its validity is not automatic: it must be justified by the nature of the role and proportionate to the aim pursued. An exclusivity clause is in principle unenforceable against a part-time employee wishing to supplement their income, but this must be checked case by case.

For a public agent, the framework is stricter. Combining activities falls under a specific authorisation regime set by public service rules: depending on the working quota and the nature of the activity, a declaration or prior authorisation from the administration may be required. This point must be verified for your specific situation.

Our reading. Before creating anything, re-read your employment contract and your collective agreement. The cost of a poorly assessed exclusivity clause is not a tax reassessment: it is a dismissal. In files where an employee consults us after the fact, the sticking point almost always comes from a forgotten clause, never from the chosen status.

The choice of status depends on your goal: testing, supplementing income, or preparing a genuine switch. Three main options stand out.

For the vast majority of side businesses starting out, the micro-entreprise is the most suitable tool: zero charges as long as you do not invoice, monthly or quarterly reporting, and a possible switch to a company the day the activity takes off. It is the entry point we recommend for testing without committing to fixed costs. For the step-by-step procedure, see our complete guide to creating a micro-entreprise in 2026.

Umbrella employment, or portage salarial to test an activity, is worth a look when you sell an intellectual service to a limited number of clients: you keep employee status, hence social protection aligned with your job, without setting up a structure. The downside is the management fee, which weighs especially on small turnovers.

This is where most errors concentrate. Two sets of thresholds, often confused, do not follow the same logic.

The micro regime thresholds#

For income received in 2026, the micro regime remains accessible as long as your turnover does not exceed:

These thresholds are assessed on the turnover of the previous year (N-1) or the year before that (N-2). Key point: leaving the micro regime is not immediate. You only switch to an actual regime if the threshold is exceeded for two consecutive calendar years, that is over both N-1 AND N-2. An isolated overrun in a single year does not make you lose the benefit of the regime.

The underestimated risk. These amounts must not be confused with the VAT base franchise. Many founders still read the old thresholds from the 2023-2025 three-year period (EUR 188,700 and EUR 77,700), frozen and outdated for 2026. Always check the date of the page you are consulting.

The VAT base franchise, a distinct regime#

The VAT base franchise exempts you from charging and remitting VAT. Its thresholds, which are lower, are entirely independent of the micro regime thresholds:

• EUR 85,000 for the sale of goods and provision of accommodation,
• EUR 37,500 for services.

You can therefore remain a micro-entreprise while becoming liable for VAT: a service-based side business exceeding EUR 37,500 must charge VAT without leaving the micro regime. This dissociation surprises many employees who venture into consulting or content creation.

The status is settled in a day. Time, however, is the constraint that makes or breaks a side business. A few operational benchmarks we see working.

1. Block fixed slots. A side business without dedicated time always ends up absorbed by daily life. Two or three recurring evenings or a half-weekend beat a vague intention.
2. Separate your tools from the start. A dedicated bank account, a dedicated email address, a phone if possible. This separation protects your duty of loyalty and radically simplifies your accounting.
3. Invoice properly from the first euro. Mandatory mentions, continuous numbering, retention of supporting documents. A poorly documented side business becomes a headache on the day of the switch.
4. Track your real profitability, not your turnover. A complementary income that costs you your evenings without generating net margin is not a project, it is a burden.

To frame the ambition and check that the model holds up before investing your weekends in it, taking the time to build a solid business plan remains the most profitable exercise, even on a small scale.

Yes, without exception. All self-employed income is reportable, even a few hundred euros a month. As a micro-entreprise, you declare your turnover to Urssaf (monthly or quarterly) and carry your income onto your tax return. Omission is not a grey area: it is concealed activity, heavily sanctioned.

What the authorities look at. The regularity of receipts on a personal account, public listings (website, social networks, marketplaces) and the consistency between lifestyle and declared income. A visible but undeclared side business is one of the easiest cases to detect.

Combining salaried income with self-employed income also affects your taxation: the two incomes add up and may move you into a higher bracket. Anticipating this effect avoids an unpleasant surprise when the tax notice arrives.

An employee consults us about a consulting activity launched in the evenings as a micro-entreprise. In the first year, a few thousand euros of turnover, almost no charges, no trade-off to settle. In the second year, the activity exceeds the VAT threshold and approaches a level where it could replace part of the salary. This is the tipping point.

At this stage, three questions structure the decision: does the micro-entreprise remain fiscally favourable once actual charges are taken into account? Does a company (SASU, EURL) provide better protection and allow remuneration to be managed? Is the order book predictable enough to leave salaried employment? No answer is universal: it depends on your margin, your family situation and your appetite for risk.

The switch is not decided on a whim or on a single good month. The signals we consider reliable:

• regular turnover over at least six to twelve months, not an isolated spike;
• a safety cushion covering several months of personal expenses;
• demand that exceeds your capacity to handle it in the evenings and at weekends;
• a business model whose net margin, including charges and contributions, approaches your net salary.

This is also when the choice of status comes back into play. Switching to a company, arbitrating between remuneration and dividends, structuring social protection: these subjects deserve a chartered accountant's view before signing. Our support for freelancers and consultants details these steps, and the page dedicated to company creation in Paris sets out the procedure to follow.

• Do not confuse the thresholds. EUR 203,100 / 83,600 to remain in the micro regime; EUR 85,000 / 37,500 for the VAT franchise. Two logics, two consequences.
• Leaving the micro regime requires two consecutive years of overrun, not just one.
• Check the freshness of your sources. The EUR 188,700 / 77,700 thresholds belong to 2023-2025 and are outdated for 2026.
• Re-read your exclusivity clause and, for public agents, the authorisation regime for combining activities.

• An employee can start a side business, most often as a micro-entreprise, subject to loyalty and any exclusivity clause.
• The 2026 micro thresholds are EUR 203,100 (sale of goods) and EUR 83,600 (services / BNC), assessed on N-1 or N-2.
• The VAT franchise (EUR 85,000 / 37,500) is a distinct regime from the micro exit threshold.
• All complementary income is reportable, without exception.
• The real limiting factor is time management, not creation.
• The switch to full time is decided on the regularity of turnover and the strength of the model, never on a single good month.