Since December 2005 it has been possible for two people to enter into a 'pacte civile de solidarité' in France, governed by article 515-1 of the French Civil Code. This new arrangement can be suitable for same sex or male/female partnerships, and brings with it a number of advantages including savings on inheritance tax.
The procedures for entering into a PACS are relatively simple and require only a declaration by the two partners, two orignal copies of which are lodged with the civil court. A French 'notaire' or 'avocat' can help with the wording and offer advice as to how you can structure the partnership arrangements - for example in relation to property and other assets held by one or both partners.
The PACS continues to exist until amended (by filing a declaration at the court) or terminated by mutual agreement; by either partner wishing to end the PACS; in the case of marriage by one of the partners; and on the death of one of the partners.
Under amended inheritance laws, valuable savings can be made if one partner leaves his/her estate (property) to the other, where before inheritance tax was payable at 60%, the high rate for bequests outside the immediate family. It is essential to take formal legal advice, depending on your status as a French resident or not, before entering into a PACS.