State income taxes are due today. When filing on paper, the Iowa Department of Revenue uses the postmark date to determine if a return was filed on time. If an individual is e-filing, the transmittal date is used.
Iowa has no paper extension forms, but if 90% of your taxes are paid by today, you automatically have until October 31st to file a return.
Income taxes are due on April 30th annually, unless the date lands on a Saturday or Sunday, in which case the deadline is the following Monday.