Kansas (KS)
April 15, 2026
October 15, 2026
✓ Automatic w/ Federal
KS — KansasKansas Personal Income Tax Extension — What You Need to Do
Filing federal Form 4868 automatically extends your Kansas return to October 15, 2026 — no separate Kansas form exists. Just enclose a copy of Form 4868 with your Kansas return when you file. But Kansas layers on its own condition: to avoid an extra penalty on top of ordinary interest, you need to have paid at least 90% of your tax by April 15, 2026.
Kansas Extension Checklist — 2026
Two things to handle. No Kansas extension form to file.
April 15, 2026
Pay At Least 90% of Your Kansas Tax
Bank Account via Kansas Customer Service Center
Kansas Customer Service Center
No K-40V needed when paying electronically.
October 15, 2026
File Federal + Kansas Return
File your federal return now and add your Kansas state return — Form K-40 — in the same session, enclosing a copy of Form 4868. Filing sooner means a faster refund. Your Kansas extended deadline is October 15.
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Kansas Late Payment Penalties — What It Costs to Wait
The extension gives you until October 15 to file. But unpaid tax starts costing you money the day after April 15.
| Charge Type | Rate | Cap | Trigger |
|---|---|---|---|
| Late Payment Penalty | 1% per month | 24% | Unpaid balance after April 15 |
| Extension Penalty | Separate penalty charge applies | — | Less than 90% paid by April 15, even with a valid extension |
| Interest | 8% per year — 0.67% per month (2026) | No cap | Accrues from April 15 on any unpaid balance |
Kansas State Extension Details
| Extension Type | Automatic with Federal Extension |
| Original Filing Deadline | April 15, 2026 |
| Extended Filing Deadline | October 15, 2026 |
| Extension Period | 6 months |
| Extension Form | None — Kansas has no separate extension request form; enclose a copy of federal Form 4868 with your K-40 |
| Return Form | Form K-40 |
| Federal Extension Required? | Yes — Kansas’s extension is tied directly to filing federal Form 4868 |
| Payment Deadline | April 15, 2026 (extension does not extend payment) |
| The 90% Rule | Pay at least 90% of your total tax by April 15, 2026 to avoid a separate penalty charge on top of ordinary interest |
| Payment Voucher | Form K-40V — check the extension payment box |
| Return Mailing Address | Individual Income Tax, Kansas Department of Revenue, PO Box 750260, Topeka, KS 66699-0260 |
| Online Payment Portal | Kansas Customer Service Center |
| State Agency | Kansas Department of Revenue |
| Late Payment Penalty | 1% per month, up to 24% |
| Interest Rate (2026) | 8% per year — 0.67% per month |
Kansas Tax Extension — Frequently Asked Questions
Do I need to file a Kansas extension form?
No. Kansas does not have a separate extension request form. Filing federal Form 4868 with the IRS automatically extends your Kansas filing deadline — just enclose a copy of Form 4868 with your completed Form K-40 when you file.
What is Kansas’s 90% rule?
Interest accrues on any unpaid Kansas tax after April 15 regardless. But to avoid an additional, separate penalty charge, you need to have paid at least 90% of your total tax by April 15, 2026 and the remaining balance by the extended due date.
What is Form K-40V — do I need it?
Form K-40V is Kansas’s payment voucher, used when mailing a check or money order — either for an extension payment or with your final return. Check the box that matches your payment type. If you pay electronically through the Kansas Customer Service Center, you don’t need it.
Does the Kansas extension cover my federal return?
No. It works the other way around — filing federal Form 4868 is what triggers your Kansas extension. There is no way to get a Kansas-only extension independent of the federal one.
What if I’m due a refund?
If you’re entitled to a refund, Kansas does not require an extension at all — there’s no penalty for filing late when no tax is due. You’ll still want to file as soon as you can to get your refund.
Which Kansas return form do I need?
Form K-40 is the Kansas individual income tax return, used by full-year residents, part-year residents, and nonresidents alike, with residency status indicated on the form itself.
Ready to File? Start Federal + Kansas
File your federal return and add Kansas state in the same session. October 15 extended deadline — secure, fast, with live support.