This adds a very important coverage to your automobile policy. This will allow your own liability limits to be used to “top-up” an underinsured vehicle you may be involved in an accident with. In Ontario the minimum liability limits are $200,00 and some American States have limits as low as $50,000, if you carried a $1,000,000 limit of liability on your vehicles this could conceivable provide you with an additional $950,000 of insurance protection.