Quick question for the group - does anyone know the correct proration methodology for Ameren Missouri Large General Service rate? I have a client with a 38-day billing period and Ameren applied what looks like a straight 38/30 multiplier to the demand charge. But the tariff language seems to suggest they should use actual days/average monthly days. Client got charged an extra $800 and I want to make sure I'm reading this right before I challenge it.
Ameren Missouri proration formula wrong?
John, you're absolutely right to question that. Most utilities should be using actual days in the period divided by the standard billing period days (usually 30). A straight multiplier like 38/30 = 1.267 is lazy math and typically overcharges the customer. Check the tariff's "billing period" or "proration" section - it should specify the exact calculation method.
I deal with Oncor here in Texas and they use actual days/30.44 (average monthly days). Each utility can be different, but John's right that straight day-count ratios usually favor the utility. Pull the full tariff and look for specific proration language. If it's ambiguous, file a complaint - regulators hate vague billing practices.