1. Is it permissible to give zakat and usurious surplus to a maternal grandfather? 2. How is the nisab determined, and is it permissible to estimate it approximately? 3. What should someone do if they do not know when their wealth reached the nisab when giving zakat for the first time? 4. Is zakat calculated on each bank account separately or cumulatively? 5. What is the percentage of zakat that must be paid on wealth?

It is not permissible to give zakat to poor ascendants, and it is obligatory to spend on them. The grandfather is among the ascendants. Usurious money should not be given to the grandfather as an obligatory expenditure. However, it can be disposed of by giving it to a deserving poor person if it is not in lieu of an expenditure. One must avoid usury, as it is forbidden, diminishes wealth, and corrupts both religious and worldly affairs.

The zakat nisab (minimum threshold) is equivalent to 85 grams of gold or 595 grams of silver. If a lunar year passes on money that has reached the nisab, the zakat due is a quarter of a tenth (2.5%). If you do not know when the year began, strive to determine it and pay the zakat for past years.

All bank accounts that generate a single type of profit are subject to zakat when a year has passed on the first nisab that was completed. If the accounts are separate in their source, those that have not reached the nisab are added to the account that has reached the nisab, and zakat is paid on them when their specific year passes, or zakat is paid on all of them when the year for the first account passes.

The zakat percentage varies depending on the type of wealth: Gold, silver, paper currencies, and trade goods are subject to a quarter of a tenth if they reach the nisab. For fruits and crops, if they reach the nisab (652 kg), one-tenth is due if they were watered by rain, and half a tenth if they were watered by effort. For livestock, zakat is due on sheep when they reach forty, for camels, one sheep for every five, and for cattle, a tabi' (one-year-old calf) for every thirty and a musinna (two-year-old heifer) for every forty.