Is zakat obligatory on a sum of money saved monthly to help with marriage expenses, and how is it calculated if the amount is continuously increasing, and is it permissible to give it to a family member?

Zakat (definition) is an obligatory act of worship and a pillar of Islam, incumbent upon anyone who possesses the nisab (definition) (the equivalent of 85 grams of gold) and upon which a full lunar year has passed. Zakat must be paid annually at a rate of 2.5% of the amount, if it reaches the nisab, taking into account the changing value of gold. It is permissible to give Zakat to relatives who are not direct ascendants or descendants, provided they are among the eight categories of eligible recipients mentioned in the Holy Quran.