Is it obligatory to pay Zakat from one's salary as soon as the nisab is reached, and is it permissible to pay it into the mosque's designated funds for the marriage of orphans and the poor?

Zakat is obligatory on money saved from salary if it reaches the nisab and a full year has passed over it. It is permissible to pay it in advance before the completion of the year if there is a benefit in doing so. It is permissible to place zakat in mosque funds designated for it only, provided that those in charge of them are trustworthy.