Rarely does an S corporation make estimated tax payments. On rare occasions the following taxes may have estimated consequences if the total of these taxes is more than an amount specified by law:

1. the tax on certain capital gains,
2. the tax on built-in gains,
3. the excess net passive income tax, and
4. the investment credit recapture tax.

For more information regarding estimated tax, refer to Form 1120S Instructions, U.S. Income Tax Return for an S Corporation, under topic Estimated Tax Payments, and Publication 542, Corporations, under topic Paying and Filing Income Taxes.

Some forms and entities have due dates other than the well-known April 15th due date. The instructions for the each type of form used will have the appropriate due date(s) noted. In general, sole proprietor's schedule of income and expenses is attached to the Form 1040 (PDF). Therefore, the due date is the same as the Form 1040 (PDF).

A Corporation may use either the calendar year, or a different tax year. An S corporation generally must use the calendar year, unless the entity can establish a business purpose for having a different tax year. The due date is March 15th for corporations on a calendar year and the 15th day of the third month following the end of the tax year for other corporations.

A partnership generally must conform its tax year of the partners unless the partnership can establish a business purpose for having a different tax year.

References:

• Publication 541, Partnerships
• Publication 542, Corporation
• Publication 334, Tax Guide for Small Business
• Entities: Sole Proprietor, Partnership, Limited Liability Company/Partnership (LLC/LLP), Corporation, Subchapter S Corporation