How is the zakaat date worked out?

“Zakaat must be calculated according to the lunar calendar and not the Gregorian calendar. Therefore, there should be a particular Islamic date every year on which Zakaat is calculated. If Zakaat is calculated according to the Gregorian calendar then one year’s Zakaat will be omitted every +-30 years.”

“In the enquired scenario, it is necessary for her to revert to her original Zakāh date, which is in Dhū al-Ḥijjah. While she may continue to discharge her Zakāh in advance during the month of Ramaḍān, she must still calculate the actual Zakāh due based on her financial standing on the original due date.”

“Who is Zakat compulsory on? Zakat is an annual obligation, due from a sane, adult, Muslim, once every lunar year. When is Zakat compulsory? An individual’s Zakat year starts on the date his wealth first equalled or exceeded the Nisab (the threshold of wealth set by Shariah for Zakat to become obligatory).”

“The principle in regard to zakaat is that one will calculate one's zakaat on his zakaat date and thereafter begin to discharge the zakaat by giving it to the poor. Before the following year's zakaat date, it is compulsory upon one to discharge all the zakaat of the previous year.”