Zakah is calculated according to the Hijri calendar

Q : Should the Hawl (one lunar year calculated from the time a property reaches the minimum amount upon which Zakah is due) for the Zakah (obligatory charity) on money and commercial commodities be considered according to the Hijri (lunar) year or the Gregorian solar year, as there is a difference of 11 days between both? If (Part No. 8; Page No. 21) the calculation of Zakah is made according to the Hijri year, what is the solution for organizations that issue their budgets and calculate their Zakah according to the solar year. Is it permissible to delay paying the due Zakah on commercial commodities beyond the Hijri year, as several contracting organizations delay the issuance of budgets six months after the passing of the year of Zakah?

A : Zakah is due on property after the passing of 12 months according to the Hijri calendar. Allah (Exalted be He) says: They ask you (O Muhammad صلى الله عليه وسلم) about the new moons. Say: These are signs to mark fixed periods of time for mankind and for the pilgrimage. It is impermissible to delay the payment of Zakah beyond the fixed time unless a legal excuse preventing the payment is verified. Allah (Exalted be He) says: the due thereof (its Zakât, according to Allâh’s Orders 1/10th or 1/20th) on the day of its harvest Allah (Exalted be He) also says: ...and perform As-Salât (Iqâmat-as-Salât), and give Zakât. This command indicates immediate response.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.