When Are State Tax Returns Due in Oklahoma?

Oklahoma is one of several states in which your state income tax return can be filed after April 15.

You probably already know that most Americans have to file their 2018 federal tax return by April 15, 2019 (as we told you earlier). For most states with an income tax (there are nine states with no income tax), the state return is also due on April 15 this year. However, some states give you more time to file — such as Oklahoma.

States With Tax Deadlines After April 15 in 2019

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StateDue Date
DelawareApril 30
HawaiiApril 22
IowaApril 30
LouisianaMay 15
MaineApril 17
MassachusettsApril 17
New MexicoApril 30 (if e-filed)
OklahomaApril 22 (if e-filed)
VirginiaMay 1

If you want an extra week after the 2018 federal tax deadline to file Oklahoma Form 511, then e-file your state return. The due date for paper Oklahoma returns is April 15, 2019 (the same as the federal due date), but the deadline is shifted to April 22 if you file your return electronically.

Can't hit the deadline? Don't worry...the Sooner State will honor any federal filing extension if no Oklahoma tax is due. (You must attach a copy of the federal extension to your Oklahoma return.) If your federal return is not extended or Oklahoma tax is owed, a six-month state filing extension can still be requested using Form 504-I. Note, however, that 90% of your Oklahoma tax liability must be paid by the original due date to avoid penalties. Interest on any outstanding balance will be charged from the original due date of the return no matter what.

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We recommend filing both federal and state returns at the same time if possible. State returns typically "piggyback" off the federal return, so it's usually easier to do them at the same time. There's also a better chance of avoiding discrepancies if you do them together. However, if that's not possible, having an extra week to file your Oklahoma return can help. It gives you more time to focus on getting your federal return off before the April 15 deadline and then to get your state return just right.

For information about other states with delayed tax filing deadlines, see 9 States Where You Can File Your State Tax Return After April 15.

Rocky Mengle

Rocky Mengle was a Senior Tax Editor for Kiplinger from October 2018 to January 2023 with more than 20 years of experience covering federal and state tax developments. Before coming to Kiplinger, Rocky worked for Wolters Kluwer Tax & Accounting, and Kleinrock Publishing, where he provided breaking news and guidance for CPAs, tax attorneys, and other tax professionals. He has also been quoted as an expert by USA Today, Forbes, U.S. News & World Report, Reuters, Accounting Today, and other media outlets. Rocky holds a law degree from the University of Connecticut and a B.A. in History from Salisbury University.