While Gap insurance is usually built into the lease one should not assume it is since every lease is different. So though many leasing companies will include gap insurance in the leasing document and payments it is not placed on all leased cars automatically.
Even if it is not automatically put on the vehicle by the leasing company your lender or lease holder may require you to purchase it separately and maintain this coverage on your leased vehicle.
GAP insurance can provide valuable protection during the early years of your car's life whether you lease a car or have an outstanding auto loan. As you are aware the value of a new car drops the minute it is driven off the lot. And unfortunately, if a negligent motorist crashes into the side of your new vehicle 2 hours after you drive home for the first time; your insurance will only cover the actual cash value of the car. Since the car is now "used" at this point, there is a good possibility that the insurance payoff for ACV will not be enough to pay off your outstanding lease (or loan) balance.
GAP insurance will pay the difference between the actual cash value of the vehicle and the current outstanding balance on your loan or lease. Some lenders and lessors will require you to carry GAP coverage until the outstanding loan/lease amount drops below the value of the vehicle, though this may only be stated in paperwork and the insurance will not be automatically placed on the vehicle by the lender.
In many cases on a leased car, the cost of gap insurance will be rolled into the lease payments. The auto dealer you are leasing from may buy a master policy from an insurance company to cover all the cars it leases and charge you for a gap waiver or gap insurance.
If you are leasing a vehicle or plan on leasing a vehicle soon you should check with the auto dealer or entity which you are leasing the car though to find out if gap insurance will be automatically rolled into your lease payment or is something you would have to add yourself separately for extra protection.