How can I file for an Idaho state extension?

To file for an Idaho state extension, you must first determine if you qualify. You qualify if you either:

Use Form 51 to determine if you qualify.

If you qualify and the amount on Line 11 of Form 51 is more than $50, you will need to make a payment. You can do this by mailing a check along with the Form 51 Voucher to the Idaho State Tax Commission, or you can pay online.  If the amount on Line 11 of Form 51 is $50 or less, you do not need to make a payment or submit Form 51 to qualify for the extension.

If you are required to make a payment to qualify for the extension, you must pay that amount online or postmark it by April 15, 2025.

If you qualify for the extension, you must file your state tax return and pay any additional tax due by October 15, 2025.

Please be aware that the extension means you can avoid a penalty for filing your return late. You will still owe interest on any tax not paid by the original due date of April 15, 2025.