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Wisconsin business tax extension

Wisconsin extends Form 4 automatically by 7 months, with no extension request and no federal extension needed. The federal extension is Form 7004, due for calendar-year corporations and for partnerships and S corporations. In general, an extension gives you more time to file, not more time to pay.

Last updated · From Wisconsin's own forms, instructions and laws, cited below

Does Wisconsin accept the federal extension?

Wisconsin extends the return automatically, with no extension request and no federal extension needed.

Wisconsin's rules for each business return, as its own instructions and laws state them:

Corporations

Return
Form 4, Wisconsin Non-Combined Corporation Franchise or Income Tax Return (Form 6 for combined groups)
Due date
The 15th day of the 4th month after the tax year ends (April 15 for a calendar year)
Extension
Wisconsin extends the return automatically, with no extension request and no federal extension needed. A corporation relying on a federal extension attaches a copy to the Wisconsin return when it files.
Extension length
7 months
Extended due date
Seven months after the original due date (or the federal due date of Form 1120, if later); with a federal extension, 30 days after the federal extended due date
Payment
The tax is due by the original due date, even with an extension.

S corporations

Return
Form 5S, Wisconsin Tax-Option (S) Corporation Franchise or Income Tax Return
Due date
The 15th day of the 3rd month after the tax year ends (March 15 for a calendar year)
Extension
Wisconsin extends the return automatically, with no extension request and no federal extension needed. A corporation relying on a federal extension attaches a copy to the Wisconsin return when it files.
Extension length
7 months
Extended due date
Seven months after the original due date (or the federal due date of Form 1120-S, if later); with a federal extension, 30 days after the federal extended due date
Payment
The tax is due by the original due date, even with an extension. To pay with the extension: Form Corp-ES, Corporation Estimated Tax Voucher.

Partnerships

Return
Form 3, Wisconsin Partnership Return
Due date
The 15th day of the 3rd month after the tax year ends (March 15 for a calendar year)
Extension
A federal extension carries over: filing Form 7004 with the IRS also extends the Wisconsin return, with no separate Wisconsin extension form. Attach a copy of the federal extension to the Wisconsin return. Without a federal extension, a partnership can still use the federal extension provision for Wisconsin by attaching a completed copy of the federal extension form or a statement naming the provision.
Extension length
6 months
Extended due date
The 15th day of the 9th month after the tax year ends (September 15 for a calendar year)
Payment
The tax is due by the original due date, even with an extension.

Estates and trusts

Return
Form 2, Wisconsin Fiduciary Income Tax for Estates and Trusts
Due date
The 15th day of the 4th month after the tax year ends (April 15 for a calendar year)
Extension
A federal extension carries over: filing Form 7004 with the IRS also extends the Wisconsin return, with no separate Wisconsin extension form. Pay the estimated Wisconsin tax by the original due date and attach a copy of the federal extension (or a statement naming the federal extension provision used) to Form 2. No extension is allowed if the estimate is not reasonable.
Extension length
5½ months
Payment
The tax is due by the original due date, even with an extension. To pay with the extension: Wisconsin Form 1-ES.

When a due date in Wisconsin falls on a weekend or legal holiday, it moves to the next business day. Wisconsin's holidays can differ from the federal ones, so a rule not tied to a federal date is given without a computed date.

When is the federal business extension due?

Corporations, S corporations, partnerships, multi-member LLCs, estates and trusts extend their federal return with Form 7004, filed by the return's original due date. The extension is automatic: no reason is needed and the IRS doesn't approve it. We e-file it for a flat $9.95. These are the 2027 dates for calendar-year 2026 returns:

Federal extension deadlines for calendar-year 2026 returns
ReturnFile the extension byExtended to
Form 1065 Partnerships & multi-member LLCs, Form 70046 months
Form 1120-S S corporations (and LLCs taxed as S corps), Form 70046 months
Form 1120 C corporations (and LLCs taxed as C corps), Form 70046 months
Form 1041 Estates & trusts, Form 70045½ months
Form 990, 990-EZ, 990-PF Tax-exempt organizations & private foundations, Form 8868May 15, 2027 is a Saturday6 months

Federal dates follow the IRS rule: a deadline on a weekend or legal holiday moves to the next business day. A fiscal-year business counts from its own year-end; see the fiscal-year deadline guide.

Tax-exempt organizations extend the 990 series with Form 8868, not Form 7004. Each return needs its own extension, so extending a business return does not extend its owners' personal returns.

Does an extension give more time to pay?

No. A federal extension moves the filing deadline only: tax owed is due by the original due date, and the IRS charges interest and the late-payment penalty on anything paid after it. Wisconsin's instructions say the same for its returns: a Wisconsin extension doesn't move the payment deadline. More in does an extension give you more time to pay?

Where are Wisconsin's forms and instructions?

On the Wisconsin Department of Revenue website, which has the current forms, instructions and online services. The rules on this page are summarized from the sources below. We e-file the federal extension; the Wisconsin return and any Wisconsin extension request go to the state.

Wisconsin extension FAQ

Does Wisconsin accept the federal business tax extension?

Wisconsin extends the return automatically, with no extension request and no federal extension needed. The extension is 7 months. A corporation relying on a federal extension attaches a copy to the Wisconsin return when it files.

When is the Wisconsin Form 4 due?

The 15th day of the 4th month after the tax year ends (April 15 for a calendar year).

Does a Wisconsin extension give more time to pay?

No. The tax is due by the original due date, even with an extension.

Does a Wisconsin business still need a federal extension?

Yes, to get more time for its federal return: Form 7004, filed by April 15, 2027 for a calendar-year corporation or March 15, 2027 for a partnership or S corporation. Wisconsin's own extension is automatic.

Sources

Filing a federal business extension this season?

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