October 15: the extension deadline for individual and C corporation returns

October 15 is the last date for those who requested an extension in April. After that day there is no further extension: a return not filed accumulates penalties.

Who is due October 15

Individual returns, Form 1040, of those who filed an extension on Form 4868. And calendar-year C corporations, Form 1120, that requested an extension on Form 7004. For both, the original due date was April 15.

Partnerships, which file Form 1065, and S corporations, which file Form 1120-S, had an extended deadline of September 15, which has passed.

What else is due that day

Form 5472 with its pro forma 1120 for foreign-owned LLCs that requested an extension, and the foreign bank account report (FBAR), whose automatic extension ends October 15.

Nonresident aliens: June 15 and December 15

A nonresident who files Form 1040-NR and did not receive wages subject to U.S. income tax withholding has an original due date of June 15, not April 15. With the Form 4868 extension, the deadline moves to December 15.

The exception: wages with withholding

If the nonresident received wages subject to U.S. withholding, the dates are the same as for a resident: April 15, and with an extension, October 15. It is a common mistake to assume every nonresident has until December.

If you cannot make it

The failure-to-file penalty is 5% of the unpaid tax for each month late, up to 25%, and if the return is more than 60 days late there is a minimum penalty. For Form 5472, the penalty is $25,000. Even if you cannot pay in full, file on time and pay what you can: the failure-to-file penalty is much larger than the late-payment penalty.