The PAYS system does not guarantee a certain level of energy savings. The margin between savings estimates and tariffed charges (i.e. the 20% immediate net savings allocated to customers) assures customers they will save more than they pay. PAYS is designed to assure customers that the cost recovery charges will stop if the upgrades fail to perform or all costs are recovered, whichever comes first. If the upgrades do stop working at no fault of the customer, the utility will suspend charges, arrange for repair or replacement, and if necessary, the utility can extend the cost recovery period to take those additional costs into account.