Yes Liberty Mutual does charge extra money for accident forgiveness to be added to your car insurance policy.
So you have to sign up for and pay for the additional accident forgiveness policy on your current car insurance policy before the accident forgiveness will take affect.
In my opinion if you don't have many accidents or any accidents at all that are your fault then it's not worth the extra cost to pay for accident forgiveness.
Liberty Mutual Insurance Accident Forgiveness is an additional coverage that you may qualify for that can be added to your auto insurance policy, where your price won't go up due to your first accident.
Liberty Mutual and other auto insurance companies offer this benefit if you are accident free and violation free for five years, whether you've been with Liberty Mutual Insurance or a prior insurance carrier.
So you can get accident forgiveness insurance if you qualify and want to pay the extra cost on your auto insurance policy.
The extra cost of accident forgiveness on your insurance policy depends on the insurance company and your current auto insurance rates.