If you want to be taken seriously by the world, you need to act like a business, in which case you need a tax ID. You can run a sole-proprietorship on your SSN. There are advantages to keeping your business separate from your personal finances. You would do well to get to the library and pick up some current books on business startups in the field you are choosing. I decided to set up an LLC. It gives me access to a business banking account, business write-offs of expenses, property owned separate from my own in case of lawsuits, etc. It does double my tax work though. Personal and business, but this is the #1 path people go these days once there is money incoming.