Rock County, WI Car Tax & Wheel Tax (2026)
In Rock County, a car purchase is taxed at 5.5% (Wisconsin's 5% state tax plus any county tax). At registration you also pay the $85 state fee plus the local wheel tax: $40 Janesville / $20 Beloit (no county wheel tax). Rock County requires no emissions test.
Verified July 2026 from official sources. How we verify fees.
What you'll pay in Rock County
- Sales tax: 5.5% (state 5% + county)
- Wheel tax: $40 Janesville / $20 Beloit (no county wheel tax) (on top of the $85 state fee)
- Emissions test: not required
- Base registration: $85 · Title: $214.50 (statewide)
How the wheel tax works
Wisconsin's wheel taxes stack — if both Rock County and your city charge one, you pay both on top of the $85 state registration fee. Sales tax is based on where the vehicle is customarily kept, not where you buy it. Note the title fee rose to $214.50 in October 2025. Estimate the purchase cost on our Wisconsin title & tax page.
Frequently asked questions
What is the wheel tax in Rock County, WI?
$40 Janesville / $20 Beloit (no county wheel tax). Wisconsin wheel taxes are charged annually at registration, on top of the $85 state fee, and county + city amounts stack.
What is the car sales tax in Rock County?
5.5% — Wisconsin's 5% state tax plus any county tax. It's based on where the vehicle is kept, not the dealer's location.
Does Rock County require an emissions test?
Rock County requires no emissions test. In Wisconsin, only Kenosha, Milwaukee, Ozaukee, Racine, Sheboygan, Washington, and Waukesha test.