Idaho Tax Extension: Everything You Need to Know

Need more time to file your Idaho state taxes?

A tax extension can give you up to six extra months to get everything in order, helping you avoid mistakes and reduce stress. But remember—an extension only delays the filing deadline, not the payment deadline.

In this guide, we’ll explain Idaho’s tax extension requirements, deadlines, and steps to help you stay on track and avoid penalties.

Ready to take control of your tax timeline?

Let’s dive in!

Why File an Idaho Tax Extension?

Filing an Idaho tax extension gives you more time to file accurately. This can be helpful if you need more time to gather documents or avoid errors. But remember, the extension only gives you more time to file, not pay. To avoid penalties and interest, you must pay at least 80% of your estimated tax by April 15.

Idaho Tax Extension Requirements

What is an Extension?

An Idaho tax extension gives you up to 6 months to file your state income tax return, moving the deadline from April 15 to October 15. But the extension only applies to filing, not paying. So, if you owe Idaho state taxes, ensure you meet the payment requirements by the original due date to avoid interest and penalties.

Idaho Extension Facts

• New Deadline: October 15
• Payment Requirement: Pay at least 80% of your estimated tax by April 15
• Forms: Use Form 51 for individual income tax or Form 41ES for business income tax if you have to make payments.

Idaho Extension Deadlines and Qualifications

When is the Deadline to File an Idaho Tax Extension?

The deadline to file an Idaho tax extension is the same as the state’s filing deadline, April 15. If you need more time to file, ensure you’ve paid at least 80% of your tax by this date.

Do I Need to File a Separate Idaho Tax Extension If I Filed a Federal Extension?

Yes, a federal extension (IRS Form 4868) does not automatically extend your Idaho state filing. You must make sure you’re eligible for an Idaho extension by paying the required tax on time. Idaho also requires you to file your state return by the extended October 15 deadline if you get an extension.

If I File an Idaho Extension, What’s My New Deadline?

With an Idaho tax extension, your new deadline is October 15. This applies to individual and business income tax returns if you meet the extension requirements.

How to Request an Idaho Tax Extension

Idaho Tax Extension Step-by-Step

1. Calculate Your Estimated Tax
2. Check Your Payment Requirement
   To avoid late payment penalties, Idaho requires you to pay at least 80% of your estimated tax by April 15. For example, if your total tax is $10,000, you must have paid at least $8,000 by April 15.
3. File the Right Form if You Have to Make a Payment
4. • File the Right Form if You Have to Make a Payment
   • Form 51
   • Form 41ES: For business income tax, use this form if you have to make a payment.
5. Pay
6. • Online: Idaho’s QuickPay to make an electronic payment.
   • Mail: If you prefer, you can mail a check with Form 51 or Form 41ES to the Idaho State Tax Commission.
   • Make the check payable to “Idaho State Tax Commission. " In the memo line, include your social security (SSN) or Employer Identification Number (EIN) and the tax year.
7. File by the Extended Deadline
   Once you get an extension, file your return by October 15. If you miss this deadline, you’ll be charged additional penalties and interest on the balance due.
8. Keep a Copy
   Save a copy of your payment confirmation and any forms filed. Idaho will only contact you if there’s an issue with your extension.

Idaho Penalties and Interest

Late Filing and Payment Penalties

If you miss Idaho’s deadlines, you may be charged:

• Late Filing Penalty: Up to 5% of the balance due per month, up to 25% of the unpaid amount.
• Late Payment Penalty: 0.5% per month on the balance due.
• Interest: Idaho charges interest on unpaid tax at 3% above the federal rate, compounded annually.

Avoid Penalties with a Valid Extension

To avoid late filing penalties, make sure your prepayments (withholdings, estimated payments, or other tax credits) are either:

• 80% of the current year’s estimated tax, or
• 100% of the previous year’s tax.

If you didn’t file the previous year, you must meet the 80% payment requirement. If you owe less than $50, no additional payment is required to get the extension.

Check out Idaho's Penalty and Interest Estimator if you need more help.

Common Questions

Do I Have to Pay Idaho Taxes When I File an Extension?

Yes. An Idaho extension only extends the filing deadline. To avoid penalties, you must pay at least 80% of your estimated tax by April 15.

Who is Eligible for an Extension in Idaho?

Anyone in Idaho, individual, corporation, or pass-through entity, can file an extension if they meet the payment requirements.

What are the Penalties for Filing Late in Idaho?

Late filing is 5% per month, up to 25% of the balance due. If you owe $2,000 and file 2 months late, you could be charged a $200 late filing penalty.

What are the Penalties for Paying Late in Idaho?

0.5% per month on the balance due, plus interest at the state rate. Meeting the 80% requirement by April 15 will help you avoid these penalties.

Should I File an Idaho Extension?

File an extension if you need more time to gather documents, avoid mistakes, or if unexpected circumstances prevent timely filing. Meeting the payment requirement will avoid interest and penalties.

"Where Idaho’s Tax Money Goes"

Idaho’s tax landscape is changing. Individual income tax revenue is down, while sales tax revenue is up, which means Idahoans are earning and spending differently. This matters because these funds pay for the state’s core functions.

Your property tax dollars go straight here: The biggest chunks fund local schools, city government, and county services. When you pay property tax, you’re directly investing in your child’s classroom, the firefighters who protect your neighborhood, and the roads you drive on every day.

If you need more time to file, extensions are available and won’t disrupt these services. This is especially true if you’re applying for property tax reduction programs or gathering documentation. The key is to understand that timely filing – original or extended – helps Idaho project and distribute these funds where they’re needed most.

Think of it this way: Every tax dollar has a job to do in your community. Knowing where these funds go helps you see why filing matters beyond the deadline.

2023 Annual Report for Idaho Department of Taxation.

Need Help? Get Personalized Service!

Stressed out with the Idaho extension process? Our team can help with both Idaho and federal extensions. Contact IRS Extension today.

Bottom Line

An Idaho extension gives you time to file your state return correctly, but you must meet the payment requirement by the original due date.

Remember, an extension only extends the filing deadline, not the payment deadline. Follow Idaho’s extension rules and avoid penalties, stay compliant and your share will help keep Idaho running.