Federal income tax returns must be postmarked by April 15 if you operate on a calendar year. If you use a fiscal year, your return is due on the 15th day of the fourth month after the end of your year. Late filing may result in stiff penalties and interest. Use Form 4868 to request an automatic four-month extension if you think you will miss the deadline. It excuses you temporarily from filing the form, but the tax is still due.
Most employers withhold a portion of workers' pay to submit to the government periodically.
Self-employed people pay an estimated tax. You have to make quarterly payments on April 15, June 15, Sept. 15 and Jan. 15. You pay tax only when you receive income. For example, if you received no income until May 10, you would pay estimated tax in June. Bankrate Inc. All rights reserved.