Tax Preparation

I want to build a ASP web site/portal to be able to offer tax preparation. to online customers. I will provide a basic template of what am looking for. The site will be Data base and table driven. it will need to prove certain tools for users like a calulator lookup functions from tax tables, EIC tables and a "save and finish later" function. I wll need to take credit cards and paypal services. All of the finish information will be held in a data base so that a real person can enter the final information into a program that will submit to the IRS.