a self-employed contractor is an employer of one person, as such he needs to pay the employer portion of healthcare insurance cost, employment tax, social secur

a self-employed contractor is an employer of one person, as such he needs to pay the employer portion of healthcare insurance cost, employment tax, social security, etc... (in the US that's another good 30% on top of salary, in France it can double the cost of employing someone). In addition the contractor does not get the benefit of bonuses, ESPP, profit sharing, 401k contributions, and takes on extra risk, all of that is worth some premium.