Thanx too you both, I thought it was just Tax d'Habitation ( but not 100% sure ) but what GnV states is true as the landlord is now asking payment for part of the Fonciéres ( although there is no mention of this in the agrrement ). Should i pay ?
If it wasn't mentioned at or before the point of signing the agreement, and the agreement is silent on the issue, I guess you could argue your point that it is not due.
In the end, it depends on the nature of your rental and any desire to extend it. A holiday let locateur doesn't pay fonciéres directly for example. It would be assumed inclusive in the rent charged.
I guess if the let was broad based and simply on the basis of nnn€ per month plus bills, without further explanation, that could imply a requirement to apportionment of the fonciéres. Taxe d'Habitation is usually levied on the person who is in residence at the 1st January of any year and similarly, any apportionment would be the responsibility of such person.