Every corporation begins as a “C” corporation and must pay income tax on the taxable income made by the corporation. After filing federal form 2553 with the IRS, a “C” corporation becomes an S corporation. The net income or loss of an “S” corporation is included in their personal tax returns and are “passed-through” to the shareholders. There is no double taxation as with “C” corporations because income tax is not taxed at the corporate level. Also known as Subchapter “S” corporations, they are limited to 100 shareholders.