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Wisconsin Individual Income Tax Filing deadlines and extensions for 2025.
If you are a tax professional working with clients who are residents or have been involved in significant business operations within Wisconsin, then they might be required to file Wisconsin State Taxes. We look at the most important tax deadlines and tax extensions for Wisconsin in 2025.
If your clients are residents or have been involved in significant business operations within Wisconsin, then they might be required to file Wisconsin State Taxes. This page outlines the most important tax deadlines and tax extensions for Wisconsin in 2025.
Wisconsin C Corporation Tax Deadlines for 2025
You must file and pay Corporate Income Taxes in Wisconsin by April 15, 2026.
Extension to File Taxes in Wisconsin for 2025
The Extension Deadline for Wisconsin corporate income tax returns is November 15, 2026.
Wisconsin automatically grants a seven-month extension on filing corporate income tax returns. This means you do not need to file for an extension in Wisconsin.
This is an extension to FILE, not an extension to PAY – payment is still due April 15, 2026.
Wisconsin S Corporation & Partnership Tax Deadlines for 2025
You must file in Wisconsin by March 15, 2026.
Extension to File S Corporation & Partnership Taxes in Wisconsin for 2025
Extension Deadlines:
Wisconsin automatically grants a seven-month extension on filing S Corporation income tax returns and a six-month extension on filing Partnership income tax returns. This means you do not need to file for an extension in Wisconsin.
This is an extension to FILE, not an extension to PAY – payment is still due March 15, 2026.
Estimated Tax Deadline for Wisconsin 2025
Estimated tax payments are due:
See Form 1ES Instructions for the amount to pay with each voucher.
Individual Tax Deadline for Wisconsin 2025
You must file and pay Individual Income Taxes in Wisconsin by April 15, 2026.
Extension to File Taxes in Wisconsin for 2025
The Extension Deadline for Wisconsin individual income tax returns is October 15, 2026.
Wisconsin will automatically grant a six-month extension on filing personal income taxes if a federal extension is filed. Wisconsin does not have its own separate extension application, so you will have to file a federal extension and attach the federal extension to the state return to receive the extension.
This is an extension to FILE, not an extension to PAY – payment is still due April 15, 2026.
Estate Tax Deadline for Wisconsin 2025
Wisconsin does not have an Estate Tax.
Farmer and Fisherman Taxes for Wisconsin 2025
If at least 2/3 of your gross income for the taxable year is derived from farming, you may pay estimated tax at any time on or before January 15, 2026. If you wait until January 15, 2026, you must pay the entire balance of the estimated tax. However, if farmers file their tax return on or before March 1, 2026, and pay the total tax at that time, they need not file estimated tax.
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The material discussed on this page is meant for general illustration and/or informational purposes only and is not to be construed as investment, tax, or legal advice. You must exercise your own independent professional judgment, recognizing that advice should not be based on unreasonable factual or legal assumptions or unreasonably rely upon representations of the client or others. Further, any advice you provide in connection with tax return preparation must comply in full with the requirements of IRS Circular 230.
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