If there are any changes in the existing policy, such as change of address or modifications to the vehicle or its use, it can be done by an endorsement by the insurance company. All you have to do is submit a letter to the insurer with proof for the required changes, and obtain the endorsement. Some endorsements may require you to pay an additional premium. Hence, you must check the correctness of the endorsement before submitting the same.
Technically, it is illegal to drive a car without insurance, and you’ll want to notify your insurer of the car as soon as possible. If you know you’re about to purchase a car, you should get quotes for auto insurance first. If you already have a policy with another vehicle, that coverage will extend to your car for anywhere between four and 30 days, depending on your policy.