Is Zakat obligatory on one who has been working for eight years and living with his family, and what is the ruling concerning the past years if Zakat was obligatory?

Zakat becomes obligatory when its conditions are met, namely owning the nisab (minimum threshold) and the completion of a hawl (one lunar year), and it is not conditional on the person being independent or having reached puberty. If a person upon whom Zakat is obligatory does not pay it on time, they must pay it immediately for all delayed years. Zakat does not lapse due to the passage of time, and if one delays it without a valid excuse, they have sinned. One should act according to their best judgment in estimating the wealth and the number of years if they are uncertain. The nisab for banknotes is the equivalent of 85 grams of gold or 595 grams of silver, and the amount due is one-quarter of one-tenth (2.5%).