Inter Company Code Transfer

Dear All,

Please help me in the following :

Issue is w.r.t the Inter Company Code Transfer :

1)do I need to separate the employee and rehire the same to another.

2)or if I can only run Transfer Action with the reason : Inter company code transfer,but the fact is system won't allow to change the Payroll Area in the mid of any month wheras except tht all his details will get changed.

3)Wht will happen in case of his leave & gratuity.....

Please suggest wht shall I do.... my more concern is towards the Payroll run and its relevant posting......

Best Regards,