Kansas splits its calendar in a way that surprises preparers: individuals file in April, but businesses file in May. For the 2025 tax year, individual returns are due April 15, 2026, while C-corporation and pass-through returns are due May 15, 2026, one month after the federal date. Any business tax owed is still due April 15. Kansas also offers an entity-level tax election worth flagging before the business deadline.

What are Kansas's 2026 tax filing deadlines?

For the 2025 tax year, the Kansas individual return (Form K-40) is due April 15, 2026. The C-corporation return (Form K-120) and the S-corporation and partnership return (Form K-120S) are due May 15, 2026, because Kansas sets business returns one month after the federal due date. Payment of any business tax liability is still due April 15, 2026.

How does Kansas's extension work?

Kansas honors the federal extension automatically and has no separate state extension form. Attach a copy of the federal extension to the Kansas return to extend the individual filing deadline to October 15, 2026; businesses get an automatic six-month extension with federal Form 7004. The extension is to file only. Paying at least 90% of the liability by the original due date avoids penalty.

What is the Kansas SALT Parity (PTE) election?

Kansas lets an S-corporation or partnership elect to pay Kansas income tax at the entity level, which moves the deduction above the federal SALT cap. The election is available for 2025 and is made on Form K-120S by checking the entity-level box. The entity-level rate is 5.58% for tax years 2024 and forward. Owners then claim the tax paid on their behalf on the K-40. Because the election lives on the business return, it is a decision to settle before the May deadline.

Who owes Kansas estimated tax?

Individuals expecting to owe $500 or more after withholding pay quarterly on April 15, June 15, September 15, 2026, and January 15, 2027 (Form K-40ES). Corporations expecting to owe more than $500 in Kansas tax make quarterly payments as well.

How does a firm handle Kansas at scale?

The trap is the split calendar. A workflow that batches every business return to the federal date will file Kansas K-120 and K-120S returns a month early, which is harmless, but it will also misjudge the payment date, which is the federal April date even though the return is due in May. Track the Kansas business filing date (May 15) and the payment date (April 15) separately, and flag SALT Parity candidates before then. See how we think about scaling tax prep workflows.

Where do these dates come from?

All deadlines and thresholds here trace to the Kansas Department of Revenue. Verify against the source before filing.