Although small business debit cards are covered by Visa Zero Liability, to qualify the customer must meet Visa requirements:
"If you experience unauthorized transactions, notify your financial institution immediately. Replacement funds are provided on a provisional basis and may be withheld, delayed, limited, or rescinded by your issuer based on gross negligence or fraud, a delay in reporting unauthorized use, an investigation and verification of a claim, and account standing and history."
If this is going on for a year, it is safe to say that the customer had a delay in reporting unauthorized use. Your business debit card agreement should provide specific details of what your obligations are for reimbursing unauthoized transactions so be sure that you eview that document and follow what you have disclosed. If your card agreement holds the customer liable because they failed to povide timely notification, then there is nothing additional that you need to do.
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