S corporations (also known as Subchapter S corporations) are corporations that elect to pass corporate income, losses, deductions, and credits through to their shareholders for federal tax purposes. Shareholders of S corporations report the flow-through of income and losses on their personal tax returns and are assessed tax at their individual income tax rates. This allows S corporations to avoid double taxation on the corporate income. S corporations are responsible for tax on certain built-in gains and passive income at the entity level.
To qualify for S corporation status, the corporation must meet the following requirements:
Be a domestic corporation
• Have only allowable shareholders
o may be individuals, certain trusts, and estates, and
o may not be partnerships, corporations, or non-resident alien shareholders
• Have no more than 100 shareholders
• Have only one class of stock
• Not be an ineligible corporation (i.e., certain financial institutions, insurance companies, and domestic international sales corporations).

In Oregon, as in other states, S corporations are recognized as pass-through entities for federal tax purposes, meaning that income, losses, deductions, and credits are passed through to shareholders instead of being taxed at the corporate level. Shareholders then report these amounts on their personal tax returns and pay tax at their individual rates, thus avoiding the double taxation that C corporations face. To be eligible for S corporation status, a corporation must be a domestic entity, restrict its shareholders to allowable individuals, certain trusts, and estates (excluding partnerships, other corporations, and non-resident aliens), have no more than 100 shareholders, maintain only one class of stock, and not fall into the category of ineligible corporations, such as certain financial institutions and insurance companies. Oregon conforms to the federal Internal Revenue Code (IRC) with respect to the recognition of S corporations, but it requires S corporations to pay a minimum tax and an excise tax based on Oregon sales. Additionally, S corporation shareholders in Oregon must pay state income tax on their share of the corporation's income.