Q. Is there a law (or advisable benchmark) regarding how long we can hire temporary staff before they must be either hired on a permanent basis or released?
A. There is no time frame that is set in stone. The risk of keeping a temporary worker on for an extended period of time arises if you classify the worker as an independent contractor. In that circumstance, you want to make sure that the worker is truly an independent contractor rather than an employee, which depends on a variety of factors.
If the individual performs services for you over a long period of time (rather than for a discrete project), that may be one factor suggesting that the worker is more like an employee than an independent contractor.