41: Corporation Income Tax Return and Instructions 2025 (2025)
Idaho · Idaho Tax Commission · Used for tax years 2025
Idaho Form 41 is the Corporation Income Tax Return for 2025. It reports income, Idaho adjustments and apportionment, taxes, credits, and payments to determine the corporation’s tax due or refund.
Who files this form
Form 41 is Idaho’s Corporation Income Tax Return. Use the 2025 form for calendar year 2025 or a fiscal year that begins in 2025.
The included instructions identify homeowners’ associations, inactive or nameholder corporations, and nonproductive mining corporations registered to do business in Idaho as corporations required to file an Idaho income tax return. They also address corporations filing as part of a unitary group.
The supplied text does not give a complete set of filing requirements.
What you'll need
Include a complete copy of your federal income tax return with Form 41. Have your business name, mailing address, EIN, and federal business activity code, also called the NAICS code, available.
Depending on your return, you may also need:
- Supporting schedules for interest, taxes deducted on the federal return, depreciation adjustments, allocated income and related expenses, and other additions or subtractions.
- Form 42 for multistate or multinational operations; Form 41A if you answer yes to any question from 7 through 7d; and Form 14 if electing water’s-edge treatment.
- Form 56 or a loss-application schedule for an Idaho net operating loss carryover or carryback.
- Form 44 for business income tax credits, credit recapture, or an eligible prior-year nonrefundable credit.
- Form 75 for fuels tax or fuel tax refunds, Form 49ER for qualified investment exemption recapture, and Form 41ESR for estimated-tax underpayment interest.
- Form ID K-1 copies if claiming tax paid by an affected business entity on the corporation’s behalf.
- A copy of Form 49E if you elected the property tax exemption for investment tax credit property, or your Idaho Reimbursement Incentive Certificate if claiming that credit.
If estimated payments were made under other EINs, provide those EINs, the amounts, and rollforwards.
How to file
- Enter the corporation’s identifying information. For a fiscal-year return, fill in the tax-year dates at the top.
- Answer questions 1 through 10 and complete the applicable income, tax, credit, and payment lines. Round amounts to the nearest whole dollar.
- Attach the complete federal return and any required forms or schedules.
- Have an authorized individual sign on behalf of the corporation. Don’t staple the return.
Mail a return with payment to:
Idaho State Tax Commission
PO Box 83784
Boise, ID 83707-3784
Mail a return without payment to:
Idaho State Tax Commission
PO Box 56
Boise, ID 83756-0056
Common mistakes
- Leaving questions unanswered. Answer each question in the questions 1 through 10 section. Incomplete returns delay processing, and unanswered questions are assumed to be “no.”
- Including a dash in the EIN. The instructions say to leave out the dash.
- Forgetting the federal return. Include a complete copy with your Idaho return.
- Reporting use tax twice. If you have an Idaho sales or use tax account, don’t report that tax on line 47. Continue reporting it on your sales and use tax returns.
- Mismatching multistate subtractions. For multistate or multinational taxpayers, line 29 must match Form 42, Part II, line 12. A mismatch will prompt an inquiry from the audit division.
- Treating a scholarship donation as reversible. A donation on line 51 reduces your refund or increases tax due. The choice cannot be changed or refunded later.
Questions people ask
Can I use Form 41 to amend a return?
Yes. Check the amended-return box, enter the number for your reason for amending, and complete the entire form with corrected amounts. Complete lines 64 through 67 as well. A net operating loss carryback requires Form 56 or a loss-application schedule; an “Other” reason requires an explanation.
What counts as an inactive or nameholder corporation?
For question 2, check “Yes” if the corporation is authorized to transact business in Idaho but has no business activity and no income attributable to Idaho.
What apportionment percentage do I enter if all activity is in Idaho?
Enter 100% on line 33. A corporation with multistate or multinational operations must instead use the factor from Form 42, Part I, line 21, and include Form 42.
Can I apply an overpayment to 2026 instead of receiving a refund?
Yes. On an original return, enter the amount you want refunded on line 63. The difference between that amount and your line 62 overpayment is applied to your 2026 tax and will not be refunded. Refunds of less than $1 are not issued.