The majority of the schools of Fiqh, namely, the Maliki, Shafi’i and Hanbali schools stance on missed Zakat for a deceased person is that Zakat must be paid from the estate when paying off any debts. Zakat will be disbursed from the estate even without a bequest for the payment of Zakat.
The Hanafi school opines that missed Zakat will not be paid from the estate unless the deceased had bequeathed the payment of Zakat. If he did enumerate missed Zakat in his bequest, Zakat will be paid from one-third of his estate after deducting funeral costs and liabilities.