Form 40 (2023): Idaho Individual Income Tax Return

Form 40 is the Idaho Individual Income Tax Return used by residents of Idaho to report their income and calculate any taxes owed to the state for tax year 2023.

Who Needs to File?

Generally, all Idaho residents must file Form 40 if their federal adjusted gross income exceeds the filing thresholds set by the Idaho State Tax Commission. You may also need to file if you owe Idaho income tax, even if your federal filing requirement is not met.

What Information Do I Need?

A. Federal Tax Return: You'll need information from your federal tax return, such as your adjusted gross income (AGI).

B. Income: Wages, salaries, tips, interest, dividends, and other forms of income received in Idaho.

C. Deductions: Itemized deductions or the standard deduction allowed by Idaho.

D. Dependents: Information for any dependents you claim.

E. Filing Status: Single, married filing jointly, married filing separately, head of household, or qualifying widow(er) with dependent children.

F. Social Security Numbers: Your Social Security number and, if filing jointly, your spouse's Social Security number.

How to File Form 40?

Electronically: Idaho offers free e-filing through its website (

Paper Form: Download the form and instructions attached below. Mail the completed form with any required attachments to the Idaho State Tax Commission.

To access the current year's Form 40: Idaho Individual Income Tax Return, click here.