634.331  Coverage of property for sale.--A home warranty may provide coverage of residential property during the listing period of such property for a period not to exceed 12 months, provided that the home warranty company charges the warranty purchaser a separately identifiable charge for the listing period coverage in an amount equal to at least 15 percent of the annual premium charged for the home warranty and the charge for such coverage is due at the earlier of the end of the listing period or the date the sale of the residential property is closed.