Can a CSP be considered to be a “conduit” like the postal service, and, therefore, not a business associate that must comply with the HIPAA Rules?

Generally, no. CSPs that provide cloud services to a covered entity or business associate that involve creating, receiving, or maintaining (e.g., to process and/or store) electronic protected health information (ePHI) meet the definition of a business associate, even if the CSP cannot view the ePHI because it is encrypted and the CSP does not have the decryption key.

As explained in previous guidance, the conduit exception is limited to transmission-only services for PHI (whether in electronic or paper form), including any temporary storage of PHI incident to such transmission. Any access to PHI by a conduit is only transient in nature. In contrast, a CSP that maintains ePHI for the purpose of storing it will qualify as a business associate, and not a conduit, even if the CSP does not actually view the information, because the entity has more persistent access to the ePHI.

Further, where a CSP provides transmission services for a covered entity or business associate customer, in addition to maintaining ePHI for purposes of processing and/or storing the information, the CSP is still a business associate with respect to such transmission of ePHI. The conduit exception applies where the only services provided to a covered entity or business associate customer are for transmission of ePHI that do not involve any storage of the information other than on a temporary basis incident to the transmission service.