What is the grace period for switching auto insurance?

If you are wanting to switch at your renewal date with your prior period, there is no grace period at the renewal date. When the policy ends it ends. If you are wanting to change when a payment is due in the middle of a policy period the insurance company will send you a notice of cancellation after you miss the payment. In my state this is 10 days from the day they mail the notice. You need to watch for this cancellation notice and note the date and time of cancellation. Most companies cancellation time is 12:01 a.m. so if the date of cancellation is 12-1 then you need to have insurance in place by this time which is one minute after midnight on 11-30.