Lying to your insurance company in the application process is never a good idea. For example, when you apply for auto insurance, your auto carrier might ask who all lives with you (in order to determine who all might be driving the car). If someone is living with you, and you do not disclose this to the insurance company, the company can void the policy after an accident. In other words, the company may not extend any coverage.

This is what happened in Nationwide Mut. Fire Ins. Co. v. Pusser, 2020-Ohio-2778. In the application process, the applicant indicated that she was the only member of her household. When her sister was driving the insured car and caused an accident, Nationwide denied coverage. The Ohio Supreme Court followed Allstate Ins. Co. v. Boggs, 27 Ohio St. 2d 216 (1971), and held:

We conclude that the insurance policy involved in this case plainly
stated that a breach of a warranty in the application for the policy
rendered the policy void ab initio [“from the beginning.”].