Filing Your 2021 Idaho State Income Taxes

Filing Your 2021 Idaho State Income Taxes
••• Viktorcvetkovic

If you are preparing to file an income tax return in Idaho, you'll want to know what forms you need, where and how to file them and how much you can expect to be taxed. Idaho has a progressive income tax structure, depending on your taxable income and filing status.

Who Must File Idaho Income Taxes?

Residents of Idaho must file an Idaho income tax return if their gross income is above a certain threshold for their age and filing status. Full-year Idaho residents are taxed on all income, whether generated within Idaho or from sources outside the state. If income from an outside source is taxed by another state, there is a potential tax credit on the Idaho income tax.

The state of Idaho defines a full-time resident as someone domiciled in Idaho for the entire tax year or who has a home in Idaho and has spent more than ​270 days​ of the current year in the state.

Part-year residents must file Idaho state taxes if the gross income they earned from all sources while living in Idaho and any Idaho-source income earned while living outside the state ​exceeds $2,500.​ A part-year resident is someone who lived temporarily in their home in Idaho or moved to or from Idaho during the tax year.

Nonresidents must file Idaho state income taxes if their gross income from Idaho sources totals more than ​$2,500.

What Are the Forms to Use?

Residents file Idaho Individual Income Tax Return Form 40. Part-year residents and nonresidents file Part-Year Resident & Nonresident Income Tax Return Form 43. Supplemental schedule Form 39R is for residents claiming any additions, subtractions or credits. Part-year residents and nonresidents use supplemental schedule Form 39NR.

If you need to file an amended return, you will refile Form 40 or Form 43, check the "amended" box and mail it to the address on the form.

The Idaho State Tax Commission Individual Income Tax Forms and Instructions booklet contains line-by-line directions for these forms.

To claim the Idaho Grocery Credit to offset the cost of sales tax paid on groceries during the tax year, submit Form 24.

You can find more individual Idaho forms and guides on the Idaho State Tax Commission website. Forms can be printed or used as a fillable PDF online. The Idaho State Tax Commission produced a video to help taxpayers locate individual forms.

What Is the Tax Rate in Idaho?

Idaho state tax is applied to the same earnings and income subject to federal tax. Idaho has a progressive individual income tax rate that was recently reduced from seven brackets to five and ranges from ​1 percent​ to ​6.5 percent​, depending on filing status and taxable income:

  • 1 percent​ for filing as single in the $1 and $1,587 range or as married in the $1 to $3,175 range
  • 3.1 percent

for filing as single in the

$1,588 to $4,762 range or as married in the $3,176 to $9,525 range * ​4.5 percent

for filing as single in the

$4,763 to $6,350 range or as married in the $9,526 to $12,701 range * ​5.5 percent

for filing as single in the

$6,351 to $7,938 range or as married in the $12,702 to $15,877 range * ​6.5 percent​ for single filers over $7,939 and married filers over $15,878

The 2021 tax rates represent a recent drop in the tax rates for all tiers. The 2021 instruction booklet contains tax tables, beginning on page 53.

What Are the Filing Deadline and Extension Process?

Idaho state tax returns must be postmarked or received by ​Monday, April 18, 2022.​ Six-month filing extension requests are due that same day. With an approved extension, your completed Idaho tax return is due by ​Oct. 15, 2022​.

If you don't owe any taxes, you don't need to file anything for an extension, but you need to mail in your complete Idaho state tax return by Oct. 15, 2022.

If you owe tax, complete Form 51, calculate your estimated tax payment and mail the form to Idaho State Tax Commission, P.O. Box 83784, Boise, ID 83707-3784. The voucher at the bottom of the form must be submitted with your tax payment by ​April 18, 2022,​ to avoid penalties and interest. Or you can pay online.

What Are the Penalties for Late Filing and Underpayment of Taxes?

If your return is past the due date without an extension, promptly file your return and pay as much of the taxes owed as you can to reduce penalties and fees. Idaho provides this flowchart to illustrate how and when penalties are enforced.

Penalties on late tax filing and delinquent taxes can range from ​0.5 percent​ per month to a maximum of ​50 percent​ of the total tax due.

In 2021, the interest rate on late Idaho tax payments is ​2 percent​ ​annually​ or .0017 monthly. You can estimate how much penalty and interest you will be charged with the Idaho State Tax Commission Penalty & Interest Estimator.

If you e-file your late return, the penalty and interest will be automatically calculated when you file.

Where Do I Mail/E-file My Idaho Return?

You may e-file free of charge through any of Idaho's suggested providers, or you may choose any commercially available tax preparation software. To access free services, you must use the links provided on the Idaho State Tax Commission website.

If you choose to file paper forms, mail them to Idaho State Tax Commission, P.O. Box 56, Boise, ID 83756-0056 and include a copy of your completed federal tax return submitted to the IRS.

How Do I Pay Taxes Due?

You can use Idaho's Taxpayer Access Point (TAP) to submit payments through Quick Pay directly from your bank account with an electronic transfer. If you prefer to pay by debit or credit card, you can use the E-Pay page of the Idaho State Tax Commission website.

To mail a check, make it payable to Idaho State Tax Commission, P.O. Box 83784, Boise, ID 83707-3784. To send an e-check, register with Access Idaho. You may also set up ACH credit through your bank by requesting the proper form via email:

If you file online, you may pay taxes due through the tax preparation software, using a credit or debit card or electronic transfer, or you may use any of the methods above.

You may request a payment plan through TAP. The Tax Commission has a video tutorial to walk you through the process.

Where Can I Check My Idaho Refund Status?

You can check your Idaho income tax refund status through the TAP system's Where's My Refund tool. You will need to enter your Social Security number and the exact amount of your expected tax refund. The tool has a graphic that tracks your return through four stages.

Allow up to ​eight weeks​ for e-filed returns to be processed before inquiring about your direct deposit refund status. Paper filers can expect an additional ​three weeks​ of processing.

If you receive a letter from the Tax Commission asking you to verify your identity, respond promptly to avoid delays in processing your refund. For tips on expediting your return, watch the Tax Commission video about what slows down your refund.

What About Idaho Taxes if You're Self-employed?

Idaho does not require self-employed individuals to make estimated tax payments, but Form 51 is available for those who wish to do so. More information regarding business income is available on the Tax Commission website.

What About Idaho Taxes if You're a Business?

Any business entity conducting business in Idaho must file an Idaho business income tax return. The business tax rate in Idaho is ​6.5 percent​. Visit the Idaho Tax Commission website for resources for business filing in the state.

Rates and dates in this article are correct as of publication. But check for any changes with the Idaho State Tax Commission before you file.