S corporations are pass-through entities, meaning that their income, losses, deductions and credits pass through the company and become the direct responsibility of the company's shareholders. The shareholders report these items on their personal income tax returns, thus S corps avoid the income double taxation that is associated with C corps.
All shareholders must sign IRS form 2553 to make the business an S corp for tax purposes. The IRS also requires S corps to meet the following requirements:
Be a domestic corporation
Have only allowable shareholders, including individuals, certain trusts and estates
Not include partnerships, corporations or non-resident alien shareholders
Have no more than 100 shareholders
Have one class of stock
Not be an ineligible corporation (i.e., certain financial institutions, insurance companies and domestic international sales corporations)