Form5S: Form5S (2025)
Wisconsin · Wisconsin DOR · Used for tax years 2025
Wisconsin Form 5S is the 2025 franchise or income tax return for tax-option (S) corporations. It reports taxes, credits, payments, and any amount owed or refund, along with shareholders’ pro rata shares of income, deductions, and credits.
Who files this form
Form 5S is Wisconsin’s franchise or income tax return for tax-option (S) corporations for tax year 2025. The form text does not give detailed rules for determining which corporations must file.
When it's due
For tax year 2025, the printed due date is the 15th day of the third month following the close of the taxable year.
If you have an extension of time to file, enter the extended due date in item B.
What you'll need
Include a copy of your federal Form 1120S, even if you had no Wisconsin activity.
Other attachments depend on your situation:
- Amended return: Include Schedule AR and an explanation.
- Solely owned QSubs or LLCs: Attach a list of their names and federal EINs, and include Schedule DE.
- Reportable transactions: Include federal Form 8886 if you filed it with the IRS.
- Items of international tax relevance: Attach federal Schedule K-2 (Form 1120-S).
- Certain Schedule 5K items: Attach Form 8825 for net rental real estate income or loss, Form 4797 for net section 1231 gain or loss, and Form 4562 for the section 179 deduction.
- Related entity expenses: Include Schedule RT if required. For the subtraction on Part IV, line 12, obtain Schedule RT-1 from the related entity and submit it with your return.
- Built-in gains: Attach the computation and supporting schedules requested in Schedule Q.
How to file
The supplied form is marked “Sample Form File Electronically.” It directs filers to the filing methods under “When and Where to File” in the instructions.
No instructions were supplied, and the form text does not provide an electronic filing link or mailing address.
Include your federal Form 1120S and applicable attachments. The form includes spaces for an officer’s signature, title, and date, and for a preparer’s signature and information.
Common mistakes
- Leaving the Wisconsin apportionment percentage blank: The form marks this as a required field in Part I, Schedule Q, and Schedule S.
- Omitting federal Form 1120S: The form says to include a copy even if there was no Wisconsin activity.
- Reporting the same withholding twice: Schedule 5K, line 13j, says not to include tax properly claimed on page 1, line 13.
- Overlooking a separate withholding form: Item D notes that a separately filed Form PW-1 may also be required when filing Form 1CNS on behalf of nonresident shareholders.
Questions people ask
Can I apply an overpayment to next year’s estimated tax?
Yes. On the 2025 return, line 21 lets you apply part or all of the overpayment on line 20 to 2026 estimated tax. Line 22 shows the remaining refund.
How do donations affect my refund or balance due?
The endangered resources donation and veterans trust fund donation each decrease your refund or increase the amount you owe.
Can I authorize someone else to discuss this return with the department?
Yes. Select “Yes” in the Third Party Designee section and complete the requested designee information.
What if I bought taxable property or services without paying sales or use tax?
The form asks whether you purchased taxable tangible personal property or taxable services for storage, use, or consumption in Wisconsin without paying a state sales or use tax. If yes, it states that you owe Wisconsin use tax.