How is the Zakat calculated for money that has not been paid for 5 years, knowing that it sometimes decreases and sometimes increases before a complete year (hawl) passes on it?

Zakat is one of the pillars of Islam, and it is not permissible to delay it past its due time. You must repent to Allah Almighty for delaying it. To determine the zakat, you need to estimate the amount that reached the zakat nisab (85 grams of gold or 595 grams of silver) in each of the past years. If the wealth falls below the nisab, the hawl (zakat year) is interrupted, and a new hawl is restarted when the nisab is met again. Regarding an increase in wealth before the completion of the hawl:

1. If it is from the growth of the nisab and of the same type, its hawl is the hawl of its origin.

2. If it is of the same type as the nisab but not from its growth, it is added to the nisab and a new hawl is calculated for it.

You must strive as much as you can to calculate the zakat for each of the past five years.