- Individuals: 2009 Form 1040 due, or file Form 4868 for automatic 6-month ex-tension. Last day to contribute to an IRA and ESA for 2009. First installment of 2010 estimated tax due. 2009 Form 709, US Gift Tax Return, due if more than $13,000 was gifted to any individual other than a spouse or charity in 2010.
- Partnerships: 2009 Form 1065 due, or file Form 7004 for automatic 5 month extension.
- Calendar Year C Corporations: First in-stallment of 2010 estimated tax due.
- Employers: File Form 941 for 1st quarter 2010.
- Partnerships & S Corporations: Form 8752 due for those using a fiscal year under a Section 444 election.
- Individuals: Second installment of 2010 estimated tax due for individuals. 2009 Form 1040 due for U.S. citizens or resident aliens living and working (or on active military duty) outside the U.S. and Puerto Rico, or file Form 4868 for 6-month extension.
- Calendar Year C Corporations: Second installment of 2010 estimated tax due.