The due date for a U.S. personal income tax return will depend on both the residence of the taxpayer, the category of the taxpayer and the type of return filed.
Filing Form 1040, “U.S. Individual Income Tax Return”
The regular due date for the filing of a U.S. personal income tax return is generally April 15th of the following year. If the 15th falls on a Saturday, Sunday or legal holiday, the due date is extended to the next business day. Since April 15th, 2018 falls on a Sunday, the due date would be extended to the next business day. Monday, April, 16th. However in Washington D.C., Monday April 16th is Emancipation Day, a legal holiday. As such, the due date is Tuesday, April 17th, 2018.
If the taxpayer is a U.S. citizen or resident whose tax home and abode, in a real or substantial sense, is outside the United States, the Regulations allow for an automatic extension until June 15th, 2018. The two-month extension is obtained by attaching an explanation to the taxpayer’s return when it is filed.
If the taxpayer is a U.S. citizen or resident whose tax home and abode are within the United States but is “out of the country” on the regular due date, the taxpayer is allowed the extra two month extension to June 15th, 2018.
Both U.S. resident taxpayers and U.S. taxpayers abroad, however, can file Form 4868, “Application for Automatic Extension of Time to File U.S. Individual Income Tax Return” for additional time to file. The filing of this form extends the due date for an additional six months in the case of a U.S. domestic filer, to October 15th, 2018. For U.S. taxpayers abroad, however, the additional extension is only 4 months to October 15th, 2018 as the extension request runs concurrent with the additional 2 month extension allowed per the Regulations. The IRS cannot refuse this extension request. The extension must be timely filed, by the regular due date, for the extension to be allowed.
Extensions can be electronically or paper filed. A paper extension will be considered timely filed if it is postmarked by the due date and mailed in an envelope that is properly addressed and has enough postage.
In addition to the six-month extension, taxpayers who are out of the country may request an additional two month extension to December 15th, 2018. This extension, however, is not automatic and at the discretion of the IRS. To request this extension, taxpayers must send a letter to the IRS (before October 15th, 2018) explaining why the additional two months is needed. If the extension is allowed the IRS will NOT respond to your request. They will only respond if they deny the request. When this extension request is denied, taxpayers have an additional 10 days to file before the return will be considered late.
Filing Form 1040NR, “U.S. Nonresident Alien Income Tax Return”
The due date for non-resident aliens, who do not earn wages subject to U.S. income tax withholding, is June 15th, 2018. Filing Form 4868 extends the due date to December 15th, 2018.
If the nonresident alien has wages, subject to U.S. withholding, the due date is April 18th, 2018. Again an extension to October 15, 2018 is available.
Form 8840, “Closer Connection Exception Statement for Aliens”
If you are filing a Form 1040NR, because you have U.S. source income, Form 8840 should be attached to Form 1040NR and filed by the due date (including extensions). If you do not have to file Form 1040NR, then Form 8840 should be filed, independently, by the due date (including extensions) for filing Form 1040NR.
The filing of an extension does not, however, extend the payment due date.
For U.S. resident taxpayers or non-resident aliens with wages subject to U.S. income tax withholding, the payment due date is April 18th, 2018.
For other non-residents aliens and for U.S. citizens and residents abroad, the payment due date is June 15th, 2018.
If a return is not timely filed, including extensions, the IRS will impose a failure-to-file penalty of 5% for each month or part of a month up to a maximum of 25%. The penalty is based on the amount of unpaid taxes, if any, owed by the filing due date.
If at least 90% of the ultimate balance due has not been paid by the original due date, the IRS will impose a failure-to-pay penalty of 0.5% per month up to a maximum of 25%. If the failure-to-file penalty and the failure-to-pay penalty both apply in any month, the combined maximum penalty for that month will be 5%.
The IRS will also impose interest on any unpaid balance until paid (this includes tax and any penalties). The interest rate is determined quarterly and is the federal short-term rate (known as the applicable federal rate or AFR) plus 3%. The short-term AFR for April 2018 is 2.12%.