An additional income of 300 euros per month does not require the creation of a complex business or heavy investment. It relies on three concrete levers: monetizing assets already owned, selling occasional skills through platforms, and optimizing aids or schemes that are often underutilized. Supplementing one’s income with this target amount requires a realistic estimate of available time and a good understanding of the tax framework applicable to additional income.
Urssaf withholding on platforms: what changes for your additional income
Before choosing an activity to earn money online, a regulatory change deserves to be understood. Starting from the last quarter of 2026, several digital platforms (Uber Eats, Wecasa, Les Sherpas, Extracadabra, Student Pop, among others) will begin to directly withhold Urssaf social contributions from the income paid to micro-entrepreneurs.
As of January 1, 2027, this withholding at source will become mandatory for all affected platforms. The contribution rates remain unchanged, but the collection method will shift completely.
For someone aiming for 300 euros monthly through these platforms, the consequence is twofold. The amount received will already be net of contributions, eliminating the risk of forgetting to declare social income. In return, the immediately available cash flow decreases, as contributions are no longer deferred to the quarterly declaration. Anticipating this mechanism avoids unpleasant surprises regarding the actual income received.
Those who combine several activities on different platforms will benefit from consulting Slouppi’s tips for earning more to compare the most profitable options after withholding.
Monetizing existing assets: additional income without extra work
The quickest lever to supplement one’s income is to exploit what one already possesses. Three categories of assets generate a regular additional income without requiring continuous work time:
- Renting out one’s home (or a room) on short-term platforms, which can cover a significant part of the monthly target depending on geographic location and seasonality.
- Renting out one’s car on services like Getaround, particularly profitable if the vehicle remains unused during the week. The income depends on the model and area, but a few monthly rentals are enough to generate a regular supplement.
- Renting out a parking space, often underestimated, which represents a stable passive income in high-demand urban areas.
These rental incomes are still subject to tax declaration, even when modest. The micro-BIC regime generally applies with a flat-rate allowance, but exceeding the exemption thresholds leads to standard taxation. Checking one’s situation on the official public service simulator avoids unpleasant adjustments.
Selling skills online: high hourly yield activities
Freelance and personal service platforms constitute the second pillar for earning additional income. Not all activities are equal in hourly yield, and this is where the choice becomes strategic.
Online tutoring, for example, boasts a high hourly yield among activities accessible without specific qualifications. A few hours per week on platforms like Les Sherpas or Superprof can help reach the goal of 300 euros monthly.
Writing, translation, or virtual assistance services operate on the same principle, with an advantage: they can be done entirely from home, without travel constraints. The micro-entrepreneur status remains the appropriate legal framework for these occasional services.
Combining with unemployment benefits: a rule to master
Since April 1, 2025, the rules for combining ARE and income from independent activities have evolved. The date of creation of the micro-enterprise (before or after the opening of rights) now modifies the calculation of the combination. An unemployed person who starts a supplementary activity without checking this point risks an unexpected reduction in their benefits.
This administrative nuance is absent from most guides on supplementary income, even though it directly concerns job seekers who wish to supplement their income.
Selling items and cashback: recoverable euros without a micro-enterprise
Selling unused items on sites like Vinted or Leboncoin does not require a specific status as long as the activity remains occasional and concerns personal goods. It is a way to quickly generate a first supplement of income without administrative formalities.
Cashback, on the other hand, works differently. Apps refund a percentage on everyday purchases (groceries, fuel, subscriptions). Taken in isolation, the amounts are small. When accumulated over a month with already planned purchases, they represent a few dozen euros without additional effort.
The combination of both approaches (occasional sales and cashback) does not replace a regular activity, but it usefully complements other levers to reach the targeted 300 euros.
Realistic budget: how much time to reach 300 euros per month
A common mistake is to add theoretical incomes without considering the actual time invested. A target of 300 euros monthly can be broken down as follows:
- Car or parking rental: potentially half of the amount, for minimal management time (a few message exchanges per week).
- Online services (tutoring, writing, services): the remainder, which is a few hours weekly depending on the hourly rate charged.
- Selling items and cashback: a variable supplement, stronger in the first months (initial clearance), then residual.
The total time to expect is between four and eight hours per week for most profiles. Beyond that, the supplementary activity encroaches on personal balance, raising the question of transitioning to a real part-time job rather than just supplementary income.
The net amount actually received will also depend on the chosen tax regime and, starting in 2027, on the automatic withholding of contributions by the platforms. Calculating one’s income after social charges and taxes remains the only reliable way to assess whether the target of 300 euros net is achieved.
