41S: S Corporation Income Tax Return and Instructions 2025 (2025)
Idaho · Idaho Tax Commission · Used for tax years 2025
Form 41S is Idaho’s S Corporation Income Tax Return for 2025. It reports income, Idaho additions and subtractions, taxes, credits, and payments to determine the amount due or overpayment.
What you'll need
Include these with your 2025 return:
- A complete copy of federal Form 1120S, including all federal Schedule K-1s.
- All Idaho Forms ID K-1. You must also provide each shareholder with an Idaho Form ID K-1.
- Schedules supporting the additions, subtractions, and allocated income that require them.
Depending on what you report, also include:
- Multistate or multinational operations: Form 42.
- Composite income: Form PTE-12.
- ABE election: Form ABE, unless the ABE box is checked and an authorized person signs the return. If the signer isn't authorized by the entity, Form ABE must include all members' signatures.
- ABE net operating loss carryover: Form 56 or a schedule showing how the loss is applied.
- Business credits or credit recapture: Form 44, and Form 70 if claiming a transferred credit.
- Fuels tax or fuel refunds: Form 75.
- Qualified investment exemption recapture: Form 49ER.
- Underpayment interest: Form 41ESR.
- Tax Reimbursement Incentive credit: A copy of the certificate.
If bonus depreciation adjustments apply, prepare a separate federal Form 4562 or a detailed computation for Idaho depreciation purposes.
How to file
Use the 2025 return for calendar year 2025 or a fiscal year beginning in 2025. For a fiscal year, complete the tax-year spaces at the top of the form.
Enter the business name, mailing address, EIN, and NAICS code. Select the return type, answer the applicable questions, and complete the return. An authorized individual must sign on behalf of the corporation.
Include the required attachments and a complete copy of your federal return. 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
- Stapling the return: The form says not to staple it.
- Including a dash in the EIN: Enter the EIN without the dash.
- Leaving questions unanswered: Unanswered questions in the Questions 1–12 section are treated as “no.”
- Including PTE-01 payments on line 60: The instructions specifically say not to include them there.
- Reporting sales or use tax twice: If you have an Idaho sales or use tax account, don't report that tax on line 54. Continue reporting it on your sales and use tax returns.
- Claiming all shareholders' credits on a composite return: Don't enter the corporation's total credit on lines 45, 46, or 47 if the corporation isn't paying tax for all shareholders.
- Expecting to reverse a scholarship donation: A donation designated on line 58 can't be changed or refunded later.
Questions people ask
Can I use Form 41S to amend a return?
Yes. Check the amended-return box and enter the reason number: 1 for a federal audit, 2 for a federal amended return, or 3 for another reason. Include an explanation for reason 3. Complete the entire form using corrected amounts and complete lines 71–74.
How should I round amounts?
Round to the nearest whole dollar. Round down amounts under 50 cents and round up amounts of 50 cents or more.
What is the difference between a composite return and an ABE return?
A composite return is a single return filed by an entity on behalf of its eligible owners. An affected business entity, or ABE, is an S corporation that elects to be taxed at the entity level.
Can I apply my overpayment to next year's tax?
Yes. On an original 2025 return, use line 70 to choose how much of the line 69 overpayment you want refunded. The remaining amount is applied to your 2026 tax and won't be refunded. Refunds of less than $1 aren't issued.