Sole Proprietorship Tax Deadlines in Wisconsin
Federal and state filing dates, extensions, and estimate schedules for 2026.
Wisconsin filing deadline
Business income reported on WI personal return.
Due: Apr 15, 2026
Extension: Oct 15, 2026
Form: Form 1
Estimated payments
Estimated payment dates: Apr 15, 2026, Jun 15, 2026, Sep 15, 2026, Jan 15, 2027.
Due: Apr 15, 2026
FAQ
Does Wisconsin require Sole Proprietorship estimated payments?
Estimated payments are scheduled for Apr 15, 2026, Jun 15, 2026, Sep 15, 2026, Jan 15, 2027.
Where can I file Wisconsin Sole Proprietorship taxes?
Use Wisconsin Department of Revenue resources at https://www.revenue.wi.gov for forms and filing instructions.