Appointment Letter Clause - Temporary Employment

We want to include a clause in our appointment letter which will suggest that the employee upon joining will be temporary/casual for a period of six months after which they will be taken on as a permanent employee . What clause can be used for this purpose ?
Also we want to know what statutories like PF , ESI & PTax will be applicable to these employees during the 6 months temporary employment

Hi,
You can include a clause as below:
Probation Period:
You shall be on probation for a period of six (6) months from the date of joining the Company. The same may however be extended or the contract of employment may be terminated, if so deemed necessary by the Management. On completion of such time, based on performance, you would be considered confirmed.