Confidentiality when dealing with the customer: disclosure to agents, representatives and third parties: confidentiality when obtaining information
Even when obtaining information from a third party, you must be careful of what information you disclose. By signalling that you have a business interest in an individual or business you are making a disclosure about them. In some circumstances disclosures of this type are permitted on the grounds that they are a disclosure for the purposes of HMRC’s functions (see IDG40400).
You need to be sensitive to the fact that you are disclosing confidential information when requesting information from third parties, and only disclose the minimum amount of information necessary.