Straight from IRS...These companies cannot control you period. If you foolishly sign a contract that controls you, they had best be taking out your taxes because you are Not an IC.
The general rule is that an individual is an independent contractor if the payer has the right to control or direct only the result of the work and not what will be done and how it will be done. The earnings of a person who is working as an independent contractor are subject to Self-Employment Tax.
You are NOT an independent contractor if you perform services that can be controlled by an employer (what will be done and how it will be done). This applies even if you are given freedom of action. What matters is that the employer has the legal right to control the details of how the services are performed.
If an employer-employee relationship exists (regardless of what the relationship is called), you are NOT an independent contractor and your earnings are generally not subject to Self-Employment Tax.