In the last 2 years, we have taken on 10 self-employed contractors on Service Contracts in part-time sales roles.  They have not been employed through an agency, but rather are retired contacts from customers/clients.  Their contract states they should work a minimum of 20 hours per week for the company and are paid a pro-rata salary plus travel expenses.

It has recently come to light that they are all working on a full-time basis. Initially, it was agreed that they would all work 25 hours per week max to allow them to also take alternative roles. 

My questions are:

– are we in danger of these guys (they are all men) demanding that they be treated as employees and able to take advantage of our benefits?

 -could I change their contracts to state ‘maximum of 25 hours per week’ and how would I do this for self-employed workers?  (Their contracts are renewed each January.)

Thanks for your advice.