Dear. As your company being the priccipal Employer, the agreeements drawn between your company and the contractor should be very clear on these statutory issues. You are also advised to collect the copies of Registration Certificates, ie relating to PF, ESI, PT Etc., and keep them for records, which will be in confirmity that you have engaged a registered contractor in all matters relating to statutory issues. By and large, the ultimate onus lies on the principal employer to discharge all such liabilities, if notices are issued to contractors and they do not pay. The best practices, some of the companies do is they deduct such amounts and take out the drafts favouring statues and have them deposited on behalf of the contractors. I hope this clarifies ur doubts and any further more queries, you are most welcome to post.