The utility only provided 18 months of billing history even though I requested 36. They claim they only retain data for 18 months in their online system. My client doesn't have copies of the older bills. How do I audit with incomplete data?
Auditing an account with incomplete billing history
Escalate the data request. The utility's online system may only show 18 months but their archived systems usually have much more. Ask to speak with the billing supervisor and request data from their archive. If they still refuse, check whether your state's PUC has a data retention rule — many require utilities to retain billing data for 3-7 years. Also, ask the client's accounts payable department. AP often has utility payment records going back years for tax purposes.
Phil N. covered the options well. One more: if you can get even partial data for the older months — like the total charges from AP records — you can extrapolate. If the current 18 months show a consistent $3,000/month overcharge, it's reasonable to estimate the same error existed in the prior 18 months. Some utilities will accept a calculated refund based on partial data if the error type is clearly continuous. Don't let incomplete data stop you from filing the claim — file with what you have and note that the actual overcharge may extend further.
Good ideas. AP had check amounts going back 4 years. Combined with the 18 months of actual billing data, I can build a solid case for the full refund period. Filing the claim with both datasets.