Idaho State Tax Commission

Individual Income Tax

You must file individual income tax returns with Idaho if you're any of the following:

  • An Idaho resident
  • A part-year Idaho resident with income from Idaho sources or income earned while an Idaho resident
  • A nonresident of Idaho with income from Idaho sources

See "Requirement to file" below.

Review these resources for more in-depth information:


You can choose to file electronically, saving time and postage.

  • These tax software packages enable you to prepare and electronically file your federal and Idaho individual income tax forms for free if you meet certain criteria.

If you don't qualify for free filing or don't want to use tax software:

Need more time to file? See if you qualify. Read our guide on valid extensions for filing.

Find out more information about Married Filing Separate with this video: How do I file separately from my spouse in Idaho?

You must file a return within three years of its original due date (often April 15), or any refund you're owed for that return will expire. You should still file your tax return if it's past the three-year limit, but we won't be able to issue any refund.

Amended returns

Double-check your tax return before you mail it or submit it through an online e-filing service. (Note: An amended return can delay completion of other returns being processed.)

If you need to correct a previously filed return, follow these steps to file an amended return:

  1. Check which return you originally filed – Form 40 or Form 43. Download a blank copy.
  2. Check the AMENDED box at the top of the blank return.
  3. Complete the return as it should have been filled out.
  4. Attach an explanation of why you're amending the return.
  5. If you need to, include copies of forms or schedules missing from the original filing.
  6. If your federal return was amended, attach a copy of Form 1040X.
  7. Mail your amended return, any supporting documentation and any payment due to:
    Idaho State Tax Commission, PO Box 56, Boise ID 83756-0056.

Requirement to file

You're required to file if your gross income is above a certain amount (see below). Gross income means all income from all sources before applying expenses or deductions. This income includes wages, interest, rents, dividends, gains from property sales, and gross business income.

Read our Idaho Source Income guide and our income tax instructions (see next section) for more information.

Idaho residents

Form 40 is the Idaho income tax return for Idaho residents. Instructions are in a separate file.

Idaho residents must file if their gross income for 2021 is at least:

Single – under age 65$12,550
Single – age 65 or older$14,250
Married (filing separately) – any age$5
Married (filing jointly) – both under age 65$25,100
Married (filing jointly) – one age 65 or older$26,450
Married (filing jointly) – both age 65 or older$27,800
Head of household – under age 65$18,800
Head of household – age 65 or older$20,500
Qualifying widow(er) – under age 65$25,100
Qualifying widow(er) – age 65 or older$26,450

Age as of the last day of 2021.

Part-year Idaho residents

Form 43 is the Idaho income tax return for part-year Idaho residents. Instructions are in a separate file.

Part-year Idaho residents must file if their total gross income from the following sources combined is more than $2,500:

  • All sources while an Idaho resident
  • Idaho-source income while a nonresident

Form 43 is the Idaho income tax return for nonresidents with income from Idaho sources. Instructions are in a separate file.

Nonresidents of Idaho must file if their total gross income from Idaho sources is more than $2,500.

Find detailed examples in our Idaho Residency Status and Idaho Source Income guides.

Tax rates

Income tax rates for 2021 range from 1% to 6.5% on Idaho taxable income. Individual income tax is graduated. This means that Idaho taxes higher earnings at a higher rate.

Keeping records

Keep copies of your tax returns and all supporting documentation for at least seven years.

Laws and rules

Learn more about Idaho individual income tax:

Page last updated August 10, 2022. Last full review of page: October 9, 2019

This information is for general guidance only. Tax laws are complex and change regularly. We can't cover every circumstance in our guides. This guidance may not apply to your situation. Please contact us with any questions. We work to provide current and accurate information. But some information could have technical inaccuracies or typographical errors. If there's a conflict between current tax law and this information, current tax law will govern.