If you can't file your Idaho state income taxes by April 15, 2019, you may be eligible to get an automatic six-month filing extension without submitting a form.
To qualify, you need to pay either an estimated 80 percent of your current year's tax liability or 100 percent of what you paid for state income taxes the prior year. You can avoid a penalty for late filing, but will be charged interest on the remaining tax until it's paid. Complete the worksheet on Idaho Form 51 , Estimated Payment of Idaho Income Tax, to see if you meet the extension requirements.
If you need to make a payment to avoid a penalty, you can mail Form 51 with your check or money order.
If you qualify for an extension to file your Idaho return, you must send the return and any payment by October 15, 2019.