I have an opportunity to work out of my home for a person who is running a marketing company out of his home.?

[doobie true]

Yes it is legal. You are contract labor. That means has not actually hired you to work for him. You work for yourself for him. You are responsible for paying your taxes and ssi just like any common business owner does. When tax time comes, he will provide you and the irs with a 1099 form and it will say how much he has paid you. Be careful and keep very good records, just like any common business owner does. Some people try to say they have paid you more than they actually did because it makes their taxes lower. A good plan is to send the irs a check about every 6 to 8 weeks for 15% of what you have made for that period of time. Send ssi a check every 4 to 6 weeks for 7% of what you have made. Then you have your state taxes. It can get to the point where you owe more to them than you are bringing in if you don't do it this way and keep putting it off.
Most contract labor that is succesful make large amounts of money. Like construction contractors and professional types like lawyers.