Subpoena Question

Hello,

I am attempting to complete my first audit on my CU's handling of subpoena and have a question regarding a potential finding. I have found that a portion of my samples including documents that were outside of the date range of the subpoena's request. The documents include statements, checks, and receipts that were clearly months outside of the date range. This is the first time I am touching subpoenas in any capacity, so I am forced to ask how big of a liability is this for the credit union?