Idaho State Tax Commission

Business Income Tax

tax.idaho.gov/busit

You must file income tax returns for your business entity if any of the following is true:

  • You're transacting business in Idaho.
  • You're registered with the Idaho Secretary of State to do business in Idaho.
  • You have income attributable to Idaho.

Filing

You can choose to file electronically, saving time and postage. These software companies provide electronic filing of business income tax forms.

Corporations

Form 41 is the Idaho income tax return for corporations.

Estimated payments

You don't have to make estimated payments the first year your corporation is in Idaho. After that, you must make estimated tax payments if both of these apply:

  • The corporation must make federal estimated payments.
  • Its estimated Idaho tax liability is $500 or more.
S corporations

Form 41S is the Idaho income tax return for S corporations.

Idaho accepts the federal approval of the S corporation election. Include either of the following with your Form 41S the first year you file it for your S corporation:

  • Federal Form 2553
  • A copy of the federal notice approving the election
Partnerships

Form 65 is the Idaho income tax return for partnerships.

Fiduciary

Form 66 is the Idaho income tax return for fiduciaries.

Estates and trusts must file Form 66 if any of the following circumstances apply:

Resident estate Gross income* of $600 or more for the current tax year
Nonresident estate Gross income* from Idaho sources of $600 or more for the current tax year
Resident trust (including grantor trust) required to file a federal return Gross income* of $100 or more for the current tax year
Nonresident trust (including grantor trust) required to file a federal return Gross income* from Idaho sources of $100 or more for the current tax year
Estate of resident individual in Chapter 7 or Chapter 11 bankruptcy** Gross income* of $9,500 or more

* Gross income as defined in Internal Revenue Code section 61(a)

** Title 11, U.S. Bankruptcy Code

Tax rates

The current Idaho business tax rate is 6.925% on taxable income.

Corporations

Corporations owe a minimum income tax of $20. Only nonproductive mining companies are exempt.

S corporations

S corporations generally pass income through to shareholders. Shareholders then pay individual income tax when they file their tax returns. Nonresident individual shareholders can have the entity pay their tax on the entity's Form 41S at the current business tax rate. The entity owes a minimum income tax of $20.

Partnerships

Partnerships generally pass income through to partners. Partners then pay individual income tax when they file their tax returns. Nonresident individual partners can have the entity pay their tax on the entity's Form 65 at the current business tax rate.

Fiduciary

Estates and trusts generally pass income through to their beneficiaries. The beneficiaries then pay individual income tax when they file their tax returns. Nonresident individual beneficiaries can have the entity pay their tax on the entity's Form 66 at the current business tax rate.

An estate or trust can also have Idaho taxable income. Fiduciary tax rates are graduated, so higher earnings are taxed at a higher rate.

Permanent Building Fund (PBF) tax

Most businesses must pay the $10 PBF tax. These businesses include:

  • C corporations must pay the $10 tax.
  • Unitary group of corporations must pay $10 for each corporation required to file in Idaho, whether the corporations file individually or the unitary group includes them in a group return.
  • S corporations must pay $10 for each shareholder for whom it pays the Idaho income tax due.
  • Partnerships must pay $10 for each partner for whom it pays the Idaho income tax due.
  • Estates and trusts must pay $10 for each beneficiary for whom it pays the Idaho income tax due.

See Idaho Code section 63-3082.

Related documents

Visit the Income Tax Hub for links to related guides.

Keeping records

Keep copies of your tax returns and all supporting documentation for a minimum of seven years. Businesses exercising the option to carryback or carry forward need to keep records for all affected years.

Laws and rules

Learn more about Idaho business income tax:

Last updated August 29, 2019. Last full review of page: August 29, 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.