Is zakat due on a salary received three months in advance, knowing that the amount saved from it can be estimated, especially if the zakat payer is accustomed to giving zakat on his wealth in Ramadan?

"Zakat on wealth is obligatory immediately if it reaches the nisab and a full year has passed over it with complete ownership. Receiving payment before performing the work is not complete ownership, so zakat is not obligatory until the work is completed. Ownership of salaries is acquired in proportion to the work performed, and zakat must be paid immediately at the end of the year. It is not permissible to delay it until Ramadan, though it is permissible to pay it in advance during Ramadan if a full year has not yet passed. There is no zakat on received salaries until they are completely owned and a full year has passed over them."