As stated above, individuals must file their income tax before April 15th. If the person has a sole proprietorship, those earnings will be included on their personal income tax form. If a person is part of a partnership, their earnings from the partnership will be included on their personal income tax form. There are no taxes on the partnership as a whole, but on the earnings passed down to the partners. Partnerships are required to file a tax return, but it is only an informational return.
Corporations are a separate legal entity and are subject to corporate tax on taxable income.
Corporate tax rates are different than personal tax rates. Corporate earnings are subject to double taxation. What this means is that corporations pay taxes on their earnings and then with after tax income they pay stockholders dividends, which are subject to capital gains tax. The dividends must be reported on the stockholder s personal tax form and are taxed at capital gains tax rates. This is what is commonly called double taxation.