Hi,
Ptax calculation is depend upon the state and INPTX function in the payroll schema. If in between the month employee is transfered then you can pass the manual ptax amount through IT15 and this amount will update the wage type /3P3 after INPTX function through custom wage type.
Or else run the transfer action from 01st day of the transfer month and capture actual transfer date in the IT41.
Regards,
Sankarsan