Although, it is acceptable to request an applicant's citizenship status on a real estate application, is it acceptable to ask that on a consumer application?

We are considering changes to our current consumer application and have found only vague information in the Regs regarding the legality of adding that question to a consumer application.

Why would it not be acceptable for a consumer app? Citizenship is not a prohibited basis, and you are allowed to inquire about an applicant's citizenship status. I've never heard that you could only do so on real estate apps.