Yes, unless you have enough money to pay for damages to others that may be caused by a motor vehicle, a surety bond, or certificate of self-insurance.

According to the Wisconsin Office of the Commissioner of Insurance, Wisconsin has a financial responsibility law with regards to motor vehicles. It is designed to make sure that any motorist licensed to drive in Wisconsin has insurance or enough money to pay for damages to others that may be caused by a motor vehicle.

These financial requirements may be met through a motor vehicle liability insurance policy, a surety bond, personal funds, or certificate of self-insurance. Details are available at the Department of Transportation, Division of Motor Vehicles (DMV) of Wisconsin or by reading through Chapter 344 of the Wisconsin Statutes.

If you decide to satisfy the requirements of the Wisconsin Financial Responsibility Law by buying auto insurance, your policy must provide the following minimum liability coverage:

• $25,000 for injury or death of one person;
• $50,000 for injury or death of two or more people; and
• $10,000 for property damage.

The law also requires uninsured motorist coverage of $25,000/$50,000 for bodily injury liability coverage only

So the answer is no, auto insurance is not mandatory in WI but only if you take care of your financial responsibility for your vehicle in one of the other state authorized ways.

If you did have insurance on your vehicle your Wisconsin policy limits would have been interpreted to provide at least the minimum limits required by the laws of the state in which you are operating your vehicle and thus would have complied with the insurance laws of the state in which you were stopped and cited for driving without insurance.

If you do not have insurance on a car and travel out of state to a state that requires vehicles on its roadways to be insured, then you need to comply with the laws of that state typically. It is important to check with states you would be driving through to make sure that driving on a surety bond or without auto insurance would not result in you being cited for being uninsured.