How is the zakat calculated for a man's money when he deposits a sum of money into his account monthly while working abroad, and is it permissible to pay it in one lump sum after several years for each year, and is the zakat amount deducted from the total amount when calculating the zakat for the following year?

It is not permissible to delay paying Zakat for years, because the principle is immediacy, and delay is not allowed except for a slight excuse. So, whoever has accumulated Zakat for years, should pay Zakat on the existing money for each year, by paying Zakat on the original amount for the first year, then paying Zakat on the remainder after deducting the Zakat of the first year for the second year, and so on. This is based on the premise that Zakat is related to money.