This sounds suspiciously like an employment coursework resit question, mainly because it's so rare that a basic scenario comes about. Forgive me if I'm wrong though, and here's a very basic lowdown;
You MUST have:
A contractual relationship between you,
You must be obliged to do the work yourself and ONLY yourself,
There must be a mutual obligation to be offered work and to accept that work which is offered to you,
You must be subject to 'sufficient' control of the hirer (A matter of fact),
and then finally you must look at the agreement as a whole (i.e: Take a commonsense view, how rare)
Facts that you haven't provided could be the difference between you being an employee or an independent contractor. As a caveat, I have no idea about buildersmate's comment on the 2 year 'limit', could be worth a look.
Good luck.