Your return is due April 15. If you cannot file on time, you can get an extension. You may use any federal extension provision for Wisconsin, even if you are filing your federal return by April 15. How to get an extension You do not need to submit a request for an extension to the department prior to the time you file your Wisconsin return. When you file your Form 1 enclose either: - a copy of your federal extension application (for example, Form 4868) or - a statement indicating which federal extension provision you want to apply for Wisconsin (for example, the federal automatic 6?month extension provision).
Note - You will owe interest on any tax that you have not paid by April 15. This applies even though you may have an extension of time to file. If you do not file your return by April 15, or during an extension period, you are subject to additional interest and penalties. If you expect to owe tax with your return, you can avoid the 1% per month interest charge during the extension period by paying the tax by April 15.