It's not that simple. You will have to do a profit and loss, you won't just pay tax on the fee, it will be less your business costs. Have a look at revenue.ie for tax advice on starting your own business and also look at AAM for business start ups (not sure if this exists but I'm sure there's plenty of advice). Banks also have documentation on starting a business.
I don't understand the other 3 posters points. The OP asked a simple question and there was no hint of tax evasion in it.