Deadline to file individual tax returns (Form 1040, 1040A, or 1040EZ) for the year 2013 or to request an Automatic Extension (Form 4868). An extension provides an extra six months to file your return. Payment of the tax is still due by April 15th. You can submit payment for tax along with the extension form.
Last day to make a contribution to traditional IRA, Roth IRA, Health Savings Account, SEP-IRA or solo 401(k) for the 2013 tax year. (However, if you get an extension, you will have until October 15th to fund a SEP-IRA or solo 401(k).)
1st quarter estimated tax payments due for the 2014 tax year.
Final deadline to file an original tax return (Form 1040) for tax year 2010 and still claim a tax refund, as refunds expire three years from the original due date of the tax return.
Final deadline to file amended tax return (Form 1040X) for tax year 2010 and still claim a tax refund. (Be sure to mail the amended return well before April 15th to make sure your tax refund will be processed in a timely manner. And be sure to obtain proof of mailing, such as a certified mail receipt.)
Deadline to file estate income tax or trust income tax returns (Form 1041) or to request an automatic 5-month extension of time to file (Form 7004).
Deadline to file partnership tax returns (Form 1065) or to request an automatic 5-month extension of time to file (Form 7004).
Final deadline for estates, trusts, or partnerships to file an amended tax return and still claim a tax refund for the year 2010, as refunds expire three years from the original due date of the tax return.