Well, I think we're digressing from the original conversation, but again, I think it depends how much you take on your own business.

I have no employees and my office is a home office. I know that there is no employer chipping in for Social Security/Medicare taxes. There is no employer contribution for federal taxes (at least, none that I know of, and if there is, I'm owed some money! :) ) - they contribute half of the 15.3% (combined) for SS and Medicare.

I agree about office space. However, when your office is in your home, it's to your benefit. My home office only covers 6% of my home, so it's not significant, but every little bit helps. I do pay for all my own supplies, and, yes, I agree, you're not saving a lot. But there's also car expenses (whether it be actual or mileage based). What I'm saying is that the only real "extra" my employer provided was health insurance and retirement benefits. While those aren't paltry, I can replace the health insurance for ~$100/mo and do my own post-tax retirement.

You have to execute the job in the most prudent manner, and if that means on their hours and with their equipment, then so be it. They should only control the outcome, not the means by which it happens. You don't have to have a yellow pages ad, dedicated business automobile or a separate office. You do have to tell the contractee what you will make, but not be controlled on how you make it. I think that's the whole problem - it's kind of vague.