There are certain case laws where the court has decided that if the contractor has its own code, then it is the responsibility of the contractor to comply, not the principal employer (PE).
But each case has its own merit. There are several types of agreements between the PE and the contractor, which are very important to judge the situation. If the PE is not paying properly to the contractor, then the case merit will be different. Again, if the PE is making payments properly but the contractor is not complying, then it is another situation.
In my opinion, the first step is to select an ethical contractor, ensure payment by the PE on time, and conduct regular checks (monthly) by the PE about the compliance status of the contractor, which possibly will make the situation smooth.
S K Bandyopadhyay (WB, Howrah) CEO-USD HR Solutions [Phone Number Removed For Privacy-Reasons] [Email Removed For Privacy Reasons] USD HR Solutions – To Strive towards excellence with effort and integrity