When is it obligatory to pay Zakat on salary: Is it in the month of Rabi' al-Thani of each year, or should one wait until Ramadan to pay Zakat on both salary and savings together, or should Zakat on salary be paid now (Rabi' al-Thani) and Zakat on savings in Ramadan?

Zakat becomes due on the salary after one year has passed over it (hawl), and it is added to the deposit for the purpose of the nisab (minimum taxable amount), but not for the purpose of the hawl. So, the deposit is subject to zakat when its year is complete, and the salary is subject to zakat when its year is complete, even if it is less than the nisab, because it reached the nisab by being added to the deposit. It is permissible to pay the zakat on the salary in advance before its year is complete, according to the preferred opinion.