What is the ruling on zakat for money that has not completed a full year (hawl)? And how is zakat paid on currencies acquired for hobby purposes whose authenticity is unknown? And is zakat obligatory on money saved to buy a car, even with a need for it?

Zakat (definition) is not obligatory on money unless a full year (hawl) has passed over it, whether it is cash, trade goods, or livestock. As for currencies, if they are not gold or silver and are in circulation, or if they are gold and silver, their zakat is obligatory if they reach the nisab (definition) and a full year has passed over them, and the amount of zakat is one-quarter of one-tenth (2.5%). As for abolished currencies that have no value or are not in use, there is no zakat on them unless they are for trade. Money saved to buy a car or anything else is subject to zakat if it reaches the nisab and a full year has passed over it.