Kentucky calendar and forms

Kentucky runs on the federal calendar. Form 740 is due April 15, 2027, the same day as the Form 1040; the four estimated payments fall on the federal dates; and a six-month extension runs to October 15, 2027. The extension is where Kentucky differs slightly: a federal Form 4868 is honored automatically, but anyone without one must send Form 740EXT by April 15. Either way the extension covers the paperwork only. Interest runs from April 15 on any unpaid tax, and a late-payment penalty is added unless at least 75% of the tax was paid by then. Refund status is at refund.ky.gov; the Department of Revenue says to allow four to six weeks for an e-filed return.

The form side is short. Full-year residents file Form 740; anyone who moved in or out, or lives elsewhere with Kentucky income, files Form 740-NP; a resident of one of the seven reciprocal states with nothing but Kentucky wages files Form 740-NP-R to get the withholding back. Behind Form 740 sit a few schedules that attach only when they apply: Schedule M for the Social Security, pension and military subtractions, Schedule A for itemizers, Schedule ITC for the Family Size Tax Credit and the personal credits, Schedule P for government pensions, and Schedule KW-2, which every filer with withholding needs because the Department no longer wants the W-2s themselves.

The 2027 filing season, dated

How the extension really works

The instructions put it in one line: “Any extension granted for federal income tax purposes will be honored for Kentucky income tax purposes.” File a federal Form 4868 and Kentucky is extended too; keep a copy, and check the extension box when the return is e-filed. Anyone who did not extend federally, or who owes Kentucky and wants to send money with the request, uses Form 740EXT, Application for Extension of Time to File, by April 15. Both routes give six months, to October 15, 2027.

Neither route extends the time to pay. Interest accrues at the tax interest rate from April 15 on whatever is unpaid; the rate is 9% for 2026 and 2027, and the Department sets each year’s rate in advance. The late-payment penalty is 2% of the unpaid tax for each 30 days, up to 20%, minimum $10, and it is waived entirely if at least 75% of the tax finally determined was paid by April 15. Late filing carries a separate 2%-per-30-days penalty up to 20%, which the extension prevents as long as the return arrives by October 15.

Estimated payments

Kentucky requires estimated payments when the tax expected for the year, after withholding, is more than $500. The safe harbor is the federal one: pay at least 90% of this year’s tax or 100% of last year’s in four timely installments and there is no penalty. For 2026 the Department “elected to mirror the federal rules for estimated tax penalty,” and Form 2210-K now has an annualized income installment section for anyone whose income arrives late in the year. The penalty goes on Form 740, line 34(a). The Department accepts estimated payments electronically through its payment portal or by mailing the 740-ES voucher.

Who gets caught: the self-employed, landlords, pass-through owners without a PTE election, and retirees whose pension and IRA income exceeds the $31,110 exclusion and had no Kentucky withholding. A single pensioner drawing $60,000 from an IRA has $28,890 of it taxed at 3.5%, about $1,011 of Kentucky tax, and if nothing was withheld that is twice the $500 line. Asking the IRA custodian to withhold Kentucky tax is the easiest fix.

The forms, in the order a filer meets them

Filing free, paying and checking a refund

About 94% of Kentucky returns are e-filed (verify), nearly all through the same software that files the federal return. The state offers two free routes. KY File, at filetaxes.ky.gov, is the Department’s own fillable-forms portal for the current-year Form 740, 740-NP or 740-NP-R, for any income: it does the basic math but offers no guidance and little error checking, it requires the federal return to be finished first, and refunds from it have been paid by paper check only (verify). Free File is the vendor program the Department links from revenue.ky.gov for taxpayers with income of $69,000 or less; each vendor sets its own limits, and for the 2025 season those ran from $32,000 (1040Now, Kentucky residents) to $89,000 (active military at several vendors), with some requiring the state return to be filed with the federal one. The 2027-season offers are to come. Kentucky has never been part of IRS Direct File.

Payments go by electronic debit through the Department’s payment portal or by check payable to “KY State Treasurer” mailed with the return to Kentucky Department of Revenue, Frankfort, KY 40619-0008 (returns with payment) or 40618-0006 (refund and no-tax returns). The Department says to allow four to six weeks for an e-filed refund, ten to fourteen weeks for a paper return and twenty to twenty-four weeks for an amended or prior-year return, which is always paid by paper check. Refund status is at refund.ky.gov, with the Social Security number and the exact whole-dollar refund amount. The Department cannot see a federal refund.

The general taxpayer line is (502) 564-4581; forms, (502) 564-3658. Taxpayer Service Centers are in Ashland, Bowling Green, Corbin, Frankfort, Hopkinsville, Louisville, Northern Kentucky (Florence), Owensboro, Paducah and Pikeville; the Form 740 instructions list each one’s address and phone number.