Perquiste - Payroll

Hi Team,

I ran the Payroll for pervious month in that period few employees total taxable amount differs from previous months even though i checked all the infotypes and his Projection Statement also in that i came to know is value of perquiste is increaing even he has been given tax exemptions .

I am not getting why his perquistes is increasing even though Tax exemption is given.

This case is only with one employee .

Pls suggest something for this .