Is zakat obligatory on the remaining amount (1700 dinars) that has completed a full year, or on the original amount (2500 dinars) from which withdrawals were made, knowing that there is another amount (1000 dinars) that has not yet completed a full year?

The method for calculating Zakat on salary has been explained previously. The questioner is only obliged to pay Zakat on money that has been in his possession for a full year (hawl) and has reached the nisab (minimum threshold) by itself or when combined with other assets. The amount mentioned (1700) is subject to Zakat when its hawl is completed. He is not obliged to pay Zakat on what he spent before the completion of the hawl.

If the questioner wishes to follow the second method, which is easier for him and more beneficial for the poor, he should pay Zakat on all the money he possesses when a full year has passed since he first acquired the nisab from it. For example, if the nisab was 1000 and he acquired it in Ramadan, then it increased to 2500, then he withdrew from it until 1700 remained, when the next Ramadan arrives, he should look at what he has saved (1700) and add to it the 1000 he had saved, and then pay two and a half percent (2.5%) of the total.