If you live regularly in France with a residence permit but which does not authorize work, your future employer must apply for a work permit at an institution called Direccte.
The application should be submitted to the regional office of that institution, by filling out an appropriate form, which is provided by the institution itself. Although this is a procedure that belongs to the employer, do not sit idly by: encourage him/her to apply for the permit and explain where he/she needs to go and what form they need to look for.
It is often the case that employers are not familiar with the procedures of employing foreigners and, despite the desire to hire you, the procedure may just seem confusing. When it’s not; it’s just a procedure like any other.
If you live illegally in France, you must first obtain a residence permit. It can be salaried or temporary. To do this, you must submit an application for a residence permit to the adequate prefecture. Since the future employer cannot offer you an employment contract (because you are illegal in France), he/she can issue you a document recognized by French law as a "promise of employment", "promise d’embauche". Explain to your employer that this is not a document with real legal obligations, but it is very important in the eyes of the French authorities. Submit this document together with the application for admission to stay in France because, logically, the granting of a residence permit must be justified. And you have an argument: you have already gotten a "promise d’embauche". Once the work permit has been obtained, you must contact the OFII (French Office for Immigration and Integration) to carry out the standard medical test for the employment of foreigners. In addition, within 3 months of the start of the employment contract, you must pay a specific tax.
On the other hand, your employer must also pay a tax because he has hired a foreigner. Taxes are discussed in the article suivant.