Kentucky Form 740-ES is the quarterly voucher you use to send estimated income tax payments to the Kentucky Department of Revenue when your income isn’t fully covered by withholding. You file it if you expect to owe more than $500 in Kentucky tax after subtracting withholding and refundable credits. The voucher itself is short; the calculation happens on the estimated tax worksheet that comes with the instructions.
Who Has to File
You need to make estimated payments if your Kentucky income tax for the year, minus withholding and refundable credits, will exceed $500.1Kentucky Department of Revenue. Underpayment of Estimated Tax by Individuals This covers full-year residents, part-year residents, and nonresidents with Kentucky-source income. Self-employment earnings, rental income, interest, dividends, capital gains, and prize winnings are the usual triggers because nothing is withheld at the source.
If your remaining liability comes in at $500 or less, no vouchers are required for the year.2Kentucky Department of Revenue. 103 KAR 15:060 – Estimated Tax; Amended Declarations; Short Years
Working Through the Estimated Tax Worksheet
The voucher asks for your name, address, Social Security number (and your spouse’s if you file jointly), the tax year, and the payment amount.3Kentucky Department of Revenue. Form 740-ES Kentucky Individual Income Tax That payment amount comes off the worksheet in the instructions.4Kentucky Department of Revenue. Instructions for Filing Estimated Tax Vouchers
- Lines 1–3: enter estimated wages subject to withholding, add all other taxable income (self-employment, rental, investment), and total the two.
- Lines 4–5: subtract adjustments to income to get estimated adjusted gross income.
- Lines 6–7: subtract either the standard deduction or estimated itemized deductions to get estimated net income.
- Line 8: multiply estimated net income by Kentucky’s flat rate of 3.5% for tax year 2026.5Kentucky Department of Revenue. 2026 Kentucky Withholding Tax Formula
- Lines 9–11: subtract personal tax credits, the Family Size Tax Credit, and the Kentucky income tax you expect to have withheld.
- Line 12: what remains is your estimated Kentucky tax for the year. If it’s $500 or less, stop.
- Lines 13–14: on Line 13a enter 90% of your current-year estimated tax; on Line 13b enter your prior-year Kentucky tax liability. Your required annual payment is the smaller number. Divide by four for each quarterly installment.
Two adjustments to watch. If your prior-year adjusted gross income was more than $150,000 ($75,000 if married filing separately), Line 13b becomes 110% of your prior-year liability rather than 100%.6Kentucky Department of Revenue. Requirement to Pay Estimated Tax Installments Farmers and fishermen use 66⅔% instead of 90% on Line 13a.
2026 Quarterly Due Dates
Calendar-year filers have four installments:3Kentucky Department of Revenue. Form 740-ES Kentucky Individual Income Tax
- Installment 1: April 15, 2026
- Installment 2: June 15, 2026
- Installment 3: September 15, 2026
- Installment 4: January 15, 2027
A due date falling on a weekend or legal holiday shifts to the next business day. Fiscal-year filers adjust based on the month their fiscal year ends. The gap between the first and second payment is only two months, and the gap between the third and fourth is four; the January payment is easy to lose track of.
How to Submit the Voucher
By Mail
Detach the voucher for the quarter you’re paying, fill in your information and the amount, and mail it with a check or money order to:
Kentucky Department of Revenue
Frankfort, KY 40620-00093Kentucky Department of Revenue. Form 740-ES Kentucky Individual Income Tax
Make the check payable to “Kentucky State Treasurer” and write your Social Security number on the face of the check.4Kentucky Department of Revenue. Instructions for Filing Estimated Tax Vouchers Don’t staple or clip them together; put both loose in the envelope.
Online
The Department of Revenue’s payment portal at epayment.ky.gov accepts estimated income tax payments by bank account (ACH debit) or credit or debit card.7Kentucky Department of Revenue. Electronic Payment Application Choose “Individual Income Tax – Estimated Payment” as the tax type. Card payments carry a service provider fee; debit card transactions cost 1.5% per transaction. Save the confirmation number as proof of timely payment.
If your bank uses ACH debit blocks, contact your financial institution and whitelist the Department of Revenue’s originator IDs before you submit an electronic check. Otherwise the transaction can bounce, and both the bank and the Department of Revenue may charge fees.
Adjusting Payments Mid-Year
If your income shifts after you’ve started paying, you can recalculate and spread the revised annual amount across whatever installments are left. The instructions set out how many that is depending on when the change happens:8Kentucky Department of Revenue. Instructions for Filing Estimated Tax Vouchers
- Change before April 1: all four installments.
- Change between April 2 and June 1: the remaining three.
- Change between June 2 and September 1: the remaining two.
- Change after September 1: the single January installment.
When income arrives unevenly, as with seasonal work or a late-year capital gain, the annualized income installment method on Form 2210-K can reduce or eliminate the required payment for specific quarters.1Kentucky Department of Revenue. Underpayment of Estimated Tax by Individuals The method recalculates each period’s income as if it had continued at the same rate all year, then applies escalating percentages of 22.5%, 45%, 67.5%, and 90% to figure each installment. If you use it for one installment, you must use it for all four.
Farmers and Fishermen
If at least two-thirds of your gross income for the current or prior tax year comes from farming or fishing, you can skip quarterly installments.4Kentucky Department of Revenue. Instructions for Filing Estimated Tax Vouchers Instead, make a single estimated payment by January 15 of the following year, or file Form 740 (or 740-NP) by March 1 and pay the full amount then.9Kentucky Department of Revenue. Income Tax Filing Date for Farmers and Fishermen Extended Taking the March 1 route means no estimated payments are required at all.
Avoiding the Underpayment Penalty
Missing or underpaying an installment triggers a penalty calculated at the state’s tax-due interest rate, 9% for calendar year 2026. It’s figured separately for each installment that came up short, then added together, so one missed quarter costs less than four.10Kentucky Department of Revenue. Penalties, Interest and Fees
You avoid the penalty if your total withholding and timely estimated payments equal at least the smaller of:6Kentucky Department of Revenue. Requirement to Pay Estimated Tax Installments
- 90% of your current-year Kentucky tax liability, or
- 100% of your prior-year Kentucky tax liability (110% if prior-year AGI exceeded $150,000, or $75,000 if married filing separately).
The prior-year safe harbor is the easier one to hit because it doesn’t depend on predicting the current year. Match last year’s Kentucky bill (or 110% of it above the income threshold) and the penalty disappears even if April brings a larger tab.
You also owe no penalty if the remaining tax after withholding and credits is $500 or less, if you had zero Kentucky liability the prior year and were a U.S. citizen or resident the whole year, or if you’re filing for a decedent’s estate or related trust within two years of the date of death.1Kentucky Department of Revenue. Underpayment of Estimated Tax by Individuals When a penalty does apply, Form 2210-K is where you calculate it and document any exception before filing your annual return.