If a person missed a Zakat payment despite having the ability to pay their Zakat, such a person will be considered sinful.

Once a command of Allah applies to a person, to delay without any genuine justification is regarded as a sin.

Imam Al-Nawawi (may Allah have mercy on him) said: “Our scholars (the Shafi’I scholars) agree that when Zakat becomes binding upon an individual who has ability to pay, he must give immediately. Delaying the payment of Zakat will make him sinful. This is also the view of Imam Malik, Imam Ahmad and the majority of scholars. Our evidence is the words of Allah, may He be exalted:
“And give Zakat” (Qur’an 2:43). This command implies that is to be paid immediately. (al-Majmu’ Sharh al-Muhadhdhab 5/335)

And Allah knows best!

Mufti Faraz Adam