Once the corporation is formed, you then must decide how you will be taxed.  The tax consequences of this selection are as follows.
1. As a stockholder in a “C Corp” all stock dividends are taxed as paid.  In addition, any income earned by your corporation is also taxed..  This is the “double tax” of corporate ownership. You can say, OK, I won’t pay myself any dividends. Unfortunately, the IRS will eventually “ask” you to pay dividends if your company is profitable.  Plus, any salary you pay yourself is taxable.
2. If you select “S Corp” then all corporate income as well as any corporate loss is taxed on your personal 1040 income by adding a Schedule C to your return and including the net gain or loss in your adjusted gross income on your Schedule 1040.  If you do pay yourself a salary, then it is taxable.  Recognizing the high startup costs and business expenses a new company has, the IRS will allow you to forego any salary for three years under some circumstances.  But you will have to pay taxes if the company succeeds.
3. A member or owner of a LLC may choose to be taxed as a “S” corporation or as a partner in a partnership.
4. If you are in a partnership, you are taxed as an individual based on your income (loss) from the business.  It is personal income and appears on your 1040 as such.