244.18. A municipality which has availed itseld of the provisions of the first paragraph of section 244.15 shall provide, in the by-law adopted under section 244.11, the terms and conditions according to which an abatement is granted as well as the rules which apply where a debtor acquires or loses the right to an abatement during a fiscal year or where the amount of the abatement varies; it may, in particular, provide that interest is added to the amount of a surtax supplement or overpayment which must, in such a case, be paid or refunded.
The abatement to which a debtor is entitled for a fiscal year, according to the data known by the municipality at the end of that fiscal year, must be granted to him before 1 March of the following fiscal year.
The municipality must inform a debtor who receives an abatement of the rules of calculation applicable and communicate to him the data which have been used with respect to his assessment unit.