Professional Tax Deducted excess bcoz of Action in mid of the Month

Dear Team,

We have a issue in Professional Tax deduction. If employee has any confirmation action in mid of the month, PT is getting deducted excess even if there is no change in Basic / PA / PSA.

There is a confirmation action in Jan, 12 and PT got deducted 200/- instead 150/-.

When I checked the log

/ZP2 Ptax basis 7,746.05

/118 PTax Basis 01 15,008.00

/119 PTax Basis 01 13,758.00

In INPTB it is mentioned as

/ZP2 Added to Basis (Last Split): 7,746.05

/3P2 22,754.05

There is no change in Basic pay of employee from his date of joining.

Can anybody please suggest on this...

Kind Regards

NAG