The corporation is one of the more complex legal structures for a business, but it also offers the most stability. If you have dreams of turning your small business into a national or international company, incorporating is typically the right move. Corporations have been around for hundreds of years, and the law involving them is well-settled. One of the most important aspects of the law that involves corporations is the tax code. The U.S. Internal Revenue Code, or IRC, creates two categories of corporations: C corporations and S corporations.