Individual income tax

tax.idaho.gov/indit

Changes for 2018 Idaho income tax returns »

Idaho residents are taxed on their total income, including income earned in another state or country. Part-year residents are taxed on all income received while living in Idaho, plus any income received from Idaho sources while living outside of Idaho. Nonresidents are taxed only on income from Idaho sources.

Tax rate

The income tax rate ranges from 1.125% to 6.925% on Idaho taxable income. Individual income tax is graduated so higher earnings are taxed at a higher rate.

Forms/publications

Form 24 (and more information on the Idaho Grocery Credit)
Form 39R, Idaho Supplemental Schedule (for residents)
Form 39NR, Idaho Supplemental Schedule (for nonresidents or part-year residents)
Form 40, Idaho Individual Income Tax Return
Form 40V, Income Tax Payment Voucher
Form 43, Idaho Part-Year Resident & Nonresident Income Tax Return
Form 51, Estimated Payment of Idaho Individual Income Tax
Form CG, Idaho Capital Gains Deduction
Form ID-MS1, the Employee's Idaho Military Spouse Withholding Exemption Certificate
Instructions packet (including tax tables for individual income tax)
Full list of current individual income tax forms and all required schedules »
Idaho Community Property

Filing requirements

Individual income tax requirements are adjusted for inflation each year, and full filing information can be found in the Individual Income Tax instructions packet. For 2018, full-year residents must file if their gross income is at least:

Single	under 65	$12,000
Single	65 or older	$13,600
Married (filing separately)		$5
Married (filing jointly)	both under 65	$24,000
Married (filing jointly)	one 65 or older	$25,300
Married (filing jointly)	both 65 or older	$26,600
Head of household	under 65	$18,000
Head of household	65 or older	$19,600
Qualifying widow(er)	under 65	$24,000
Qualifying widow(er)	65 or older	$25,300

Part-year residents must file an Idaho income tax return if their gross income from all sources while a resident and gross income from Idaho sources while a nonresident is more than $2,500.

Nonresidents must file an Idaho income tax return if their gross income from Idaho sources is more than $2,500. This includes special-case Idaho residents, who are domiciled in Idaho but are considered nonresidents for income tax purposes. Special-case Idaho residents don't have to file an Idaho income tax return if they're absent from the state for at least 445 days in a 15-month period. However, they must meet certain qualifications. Contact us if you have questions.

Gross Income means all income from all sources before applying expenses or deductions. This includes compensation for services, gross income of a business, interest, rents, dividends, and gains from the sale of property. It also includes a partner's or shareholder's share of the gross income of a partnership or S corporation, which is different than the net amount reported on the federal Schedule K-1.

Filing deadlines

State

Individual income tax returns must be either postmarked or e-filed by April 15, or by October 15 for extended returns. However, if either of these two dates falls on a weekend or legal holiday, the tax return or extension must be filed by the next day that is not a Saturday, Sunday, or legal holiday. Income tax returns should be mailed to:

Idaho State Tax Commission
PO Box 56
Boise ID 83756-0056

Federal

Taxpayers who live in Idaho and are mailing their federal individual income tax return, should mail it to the address listed on the Internal Revenue Service website.

E-filing

We recommend that taxpayers save time and postage by e-filing their tax returns and payments. Our Free Electronic Filing page lists several companies that offer free state and federal income tax filing.

Those who need help completing their tax returns can go to our Free Tax Help page, which lists neighborhood volunteer sites for all low-income taxpayers and senior citizens with simple returns.

Extension to file

Discover the top five extension misconceptions about a "valid extension of time" for your individual income tax return.

Amending a return

Sometimes it's necessary to change, correct, or update a return that's already been filed. To do this, the income tax return must be "amended," which is generally done by mail. However, the amended return can be filed electronically if the original return was filed electronically. Here are the steps for amending an Idaho income tax return:

Select the right form — Full-year Idaho residents must amend income tax returns by completing a corrected Form 40. Part-year Idaho residents and Idaho nonresidents must complete a corrected Form 43.
Check the box for an amended return in the upper-left corner of the page, complete the form, and attach information that explains why the return is being amended.
Attach the following documents to your Idaho amended return:
- A full copy of Form 1040X if your federal return was amended,
- Copies of all 1099s and/or W-2s that weren't included with the original return, and
- Any required payment.

Refunds

There's a three-year expiration date for claiming a refund, beginning on the original due date of your income tax return. The "original due date" is the April 15 following the tax year (except when it falls on a weekend or holiday). Extensions of time to file don't change the original due date for the three-year refund claim period; after that time, a refund won't be issued.

Taxpayers can track their refund status during processing, by visiting Idaho Refund Status. If the refund is less than expected, it could be due to unpaid court fines, child support, or other legal obligations.