Wis. Admin. Code Public Service Commission PSC 134.12
Reading of all meters used for determining charges to customers shall be scheduled monthly, bimonthly, quarterly, or semi-annually. An effort shall be made to read meters on corresponding days of each meter-reading period cycle. The meter-reading date may be advanced or postponed not more than 5 days without adjustment of the billing for the period. Bills for service shall be rendered within 40 days from the reading of the meter except as may be otherwise specifically authorized by the commission. The utility may permit the customer to supply the meter readings on a form supplied by the utility, provided a utility representative reads the meter at least once each 6 months and when there is a change of customer. The utility shall make reasonable efforts to read the meters of customers who cannot be available during normal business hours.
Wis. Admin. Code Public Service Commission PSC 134.12