How is zakat calculated on money accumulated over four years, knowing that the salary has changed several times during this period, and must zakat be paid for each year separately or on the total amount?

The method of calculating zakat (definition) is easy and straightforward, and it does not depend on knowing the salary's value, the date of its increase, or the amount spent from it. Zakat is obligatory on accumulated money from salary if two conditions are met: 1. The accumulated money reaches the equivalent of 85 grams of gold or 595 grams of silver (the nisab (definition)). 2. This nisab remains with the muzakki (the person paying zakat) for a full lunar year.

If the money reaches the nisab and a year has passed over it, zakat becomes obligatory on it, and its amount is one-quarter of one-tenth (2.5%). Accordingly, the woman should check in any lunar year and month thereof if she has accumulated from her salary and other sources an amount equivalent to the nisab. Then, she should check if this nisab remained with her for a full lunar year or not. If it remained for a year, she should pay one-quarter of one-tenth from it for each year. If the money reached the nisab and a year has passed over it in all previous years, she should pay one-quarter of one-tenth for each year, and zakat does not lapse due to the passage of time.