Secure web forms? (Bank account, social security numbers, etc.)

I'm a developer with an agency that works exclusively in building and hosting WordPress sites. We've got a client who wants a credit finance application form that requests social security numbers and banking information. I'm not about to build this in a WordPress site, so I'm trying to find a 3rd party hosted service that can handle the transmission and storage of this data securely, as we don't want to deal with the PCI compliance issues of handling this in-house. I thought HN might be a good place to solicit recommendations. I've already hit up Google searches but am coming up empty with solutions that allow for the storage of this type of data (even for a short time), and/or even claims to be PCI compliant. Any advice would be welcome. Thanks.