Is Zakat obligatory upon a 66-year-old widow who has a fluctuating and diminishing bank balance of (5,500 Dinars), and what is the amount of Zakat that must be paid if it is obligatory?

The mother must pay Zakat on her money if it reaches the nisab (threshold) and a full year (hawl) has passed over it, even if it decreased during the year. This is required annually. The nisab is estimated at the equivalent value of 85 grams of gold or 595 grams of silver, and the amount of Zakat due is 2.5%. If the money falls below the nisab at the end of the year, then no Zakat is due on it.