You may need to file an extension of time to file. You can do this by filing Indiana's extension Form IT-9 or by accessing DORPay, the Department of Revenue’s s online payment service.
Properly filing an extension of time to file only allows you to file your tax return after the original due date, April 15. If you owe, at least 90% of the tax due should be paid by the original April due date to avoid incurring a late payment penalty.
See Information Bulletin #18 and the extension for time to file website for more information, or contact the Department of Revenue.