What actually happens
An employee who lives in Ohio and performs work in Kentucky sits in two tax systems at once. The residence state claims the right to tax all of a resident's income wherever earned; the work state claims the right to tax income sourced within its borders. Kentucky and Ohio resolved that overlap by agreement: the work state gives up its claim on commuters' wages entirely.
The certificate is not optional
Reciprocity does not apply automatically because the employee's address is in Ohio. It applies when the employee gives you a signed 42A809 (Certificate of Nonresidence). Until that form is in your hands you are required to withhold Kentucky tax, and an auditor will ask to see it. The form stays in your records; it is not filed with the state.
Unemployment insurance goes to one state only
Income tax can be split between states. Unemployment insurance cannot. Under the localization test used by every state, an employee whose services are performed entirely in Kentucky is covered by Kentucky for unemployment purposes, and all wages are reported there — regardless of where they live, where you are headquartered, or which state's income tax you withhold. Kentucky's 2026 taxable wage base is $12,000. The four-factor test in order.
Local taxes are a separate problem
Kentucky: Kentucky cities, counties and school districts levy occupational license (payroll) taxes ranging roughly 0.008%-2.5% (e.g., Louisville Metro, Lexington-Fayette). These are administered locally and are NOT covered by Kentucky's state reciprocity agreements -- reciprocal-state residents still owe local occupational tax on Kentucky work.
Ohio: Ohio has the most extensive local income tax system in the country -- roughly 600 municipalities and 180+ school districts levy income taxes, withheld by employers. Municipal tax is generally owed where the work is physically performed (subject to a 20-day occasional-entrant rule); school district tax is generally owed based on the employee's residence school district (Form IT 4 identifies it). CRITICAL: Ohio's state reciprocity agreements do NOT exempt a nonresident from Ohio MUNICIPAL income tax on work performed in an Ohio city.
What you have to register for
| Obligation | State | Agency |
|---|---|---|
| Income tax withholding | Ohio | Ohio Department of Taxation |
| Unemployment insurance | Kentucky | Kentucky Office of Unemployment Insurance (Education and Labor Cabinet) |
Frequently asked
Do Kentucky and Ohio have a reciprocal tax agreement?
Yes. Kentucky exempts Ohio residents from Kentucky income tax withholding on wages, provided the employee files 42A809 with their employer. Without that form on file the employer must still withhold Kentucky tax.
Which state's income tax should be withheld?
Ohio. Under the agreement the wages are taxable only by the state of residence, so you withhold Ohio tax and stop withholding Kentucky tax once the certificate is filed.
Which state gets the unemployment insurance wages?
Kentucky. Unemployment coverage is never split between states for a single job. The localization test assigns the whole job to the state where services are performed, which here is Kentucky, regardless of residence or where the employer is headquartered.