Is it permissible to give 10% of the deposited salary profits as an annual Zakat instead of 2.5% of the principal amount, especially if the entire amount will be spent soon on buying and furnishing an apartment?

If the money in the bank reaches the nisab (threshold) and a full hawl (lunar year) passes over it, then zakat is obligatory on both the principal and the profit, at a rate of 2.5% (one-quarter of a tenth). It is not sufficient to give 10% of the profits only. If the bank is interest-based (ribawi), zakat is obligatory only on the principal amount. The interest-based profits must be disposed of by giving them to the poor and needy, along with repenting and withdrawing the money from the bank.