A customer has requested a letter that states his current account balance so that he can provide it at auction for the purpose of purchasing real estate. We believe this could be a privacy issue. Thoughts?

If the customer wants it and you provide it to the customer, how is it a Privacy issue? What the customer does with this information is up to them. Privacy prohibits YOU from sharing that information in some situations, but it doesn't prohibit them from sharing it.

Address the letter to the customer. What they do with it after is their own business.

Your respondents have both offered good advice, but my guess is that your customer was asked to obtain a letter of credit from your bank, not a letter showing his bank balance. The latter would mean something between very little and nothing at all.

While I agree with Ken, I've found it depends on the Auction House. I've received several of these type of requests over the years, and some actually just want a letter of reference from the bank.

Just so there's no confusion, I usually have the customer bring in a copy of the Auction House bidder requirements.