FormU: Underpayment of Estimated Tax by Corporations (2024)
Wisconsin · Wisconsin DOR · Used for tax years 2024
Wisconsin Form U calculates a corporation’s underpayment of estimated tax and the interest due for 2024. It also includes an annualized income installment worksheet and a section for calculating total amounts due when a return is filed after the unextended due date and shows tax
Who files this form
Wisconsin Form U is for corporations calculating underpayment of estimated tax and interest on that underpayment. The form directs filers to submit it with Wisconsin Form 4, 4T, 5S, or 6.
Complete Part II only if your return is filed after the unextended due date and shows tax due. Complete Part III only if you use the annualized income installment method to calculate required installments.
When it's due
For tax year 2024, Part II, line 21 describes the amount due as payable on the 15th day of the 3rd or 4th month after the end of the taxable year. The form text does not explain which month applies to each filer.
The form refers to the instructions for estimated tax installment due dates. Those instructions are not included in the supplied text.
What you'll need
Have the information needed for these form entries ready:
- Corporation or designated agent name and federal employer ID number.
- Your Wisconsin Form 4, 4T, 5S, or 6, with which Form U must be filed.
- 2024 net tax, economic development surcharge, refundable credits, and Wisconsin tax withheld.
- 2023 net tax, economic development surcharge if applicable, and refundable credits for the prior-year calculation.
- Estimated tax and surcharge payments, including payment dates used to calculate interest.
- If using Part III, Wisconsin net income for each period, adjustments, and refundable and nonrefundable credits.
- If completing Part II, payment amounts and the date the return was filed.
How to file
File Form U with Wisconsin Form 4, 4T, 5S, or 6. The supplied form does not give a mailing address or electronic filing directions.
Enter the total from Part I, line 17 on the line provided on your tax return, unless the return is filed after the unextended due date and shows tax due. In that case, carry the total to Part II, line 22.
If completing Part II, enter the line 26 total on the line provided on your return and increase the “Amount Due.”
Common mistakes
- Do not include estimated tax and surcharge payments in the refundable credit entries.
- If Part I, line 1e is less than $500, enter $0 and go to Part II if applicable. Do not complete line 2 when line 1e is $0.
- Complete Part II only when the return is not filed by the unextended due date and shows tax due.
- If using the annualized income method, complete Part III first and carry line 47 amounts to Part I, line 6.
- In Part III, finish one column through line 47 before starting the next column.
- For a tax year shorter than 12 months, follow the instructions rather than dividing line 4 by four.
Questions people ask
What interest rate does Part I use?
Lines 15 and 16 calculate interest at 12% per year, using the amounts and number of days specified on the form.
When can I use the smaller of the current-year and prior-year amounts?
Line 4 says to enter the smaller of line 2 or line 3c if 2024 net income is less than $250,000 and the 2023 return covered 12 months. Otherwise, enter line 2. Tax-option (S) corporations making the entity-level tax election are directed to the instructions.
Do I need to complete the annualized income worksheet?
Complete Part III only if you calculate required installments using the annualized income installment method.
What late-filing charges are listed?
If the return is filed late without an extension or after the extended due date, line 25 lists a penalty of 5% of net tax due for each month or fraction of a month the return is late, up to 25%, plus a $150 late fee.