As a freelancer, the cost to cover my taxes/social security will be calculated into any offer i give. I am in effect employing myself and you are contracting out an employee of my company. The rate given will need to cover the costs of my employees taxes and social security. True i can contract out myself to multiple clients per month and lower my rate by splitting the SS taxes between them. but, in Greece, you run a high risk of work being canceled/delayed and exposing yourself to tax liabilities. Don't get me started on companies that want you to cut an invoice then pay you months later. Putting yourself into a situation where you have income on the books, but not in the hand is a bad idea.