Most of the answers are not appropriate. when we are talking about contract worker, please be specific what kind of work you are demanding from them and who is going to be the decession maker or primary employer. If your company will be held as an employer if you have all the adminsitrative and management control over the workers, your company will be liable for every legality and payments and the role of agent or contractor plays no role. Read Hussain Bhai calicut case citation.
- If you do a renewable contract, the same will be invalid, read Uma devi case citation
- If you hire workers for a period of less than 240 days and give them a rest and again hire them or any one, you will be liable for unfair labour practice, read TATA Motors case, Mumbai High court.
In simple term only involve an agent or contractor, if you have a job which cannot be performed by you or you do not have specialization. Hire on your direct payroll.