Question:
When does zakāt become obligatory on specified (mansūṣ) items?
Source: Fatāwā Amunpuri by Shaykh Ghulam Mustafa Zaheer Amunpuri
Answer:
Zakāt on the specified (mansūṣ) items becomes obligatory when:
① They reach the prescribed niṣāb (minimum threshold).
② A lunar year passes over them.
Exception: For agricultural produce, the passing of a year is not a condition.
Scholarly Consensus:
❀ ʿAbd al-Raḥmān ibn Ibrāhīm al-Maqdisī رحمه الله (624 AH):
لا زكاة فى شيء من ذلك حتى يبلغ نصابا، وذلك ثابت بالإجماع والأخبار الصحاح
“Zakāt is not obligatory on any of these items until they reach the niṣāb. This is established by consensus and authentic reports.”
(al-ʿUddah Sharḥ al-ʿUmdah, 136)

Zakāt is due on specified items only after they reach the niṣāb and a year has passed, except in the case of crops, where zakāt is due at the time of harvest.