I understand Reg E only applies to consumer accounts. But what about a DBA account set up (for example) John Smith DBA Smith's Cafe. Social Security Number is used rather than EIN. Thanks.

This is where a trip to the definitions in the regulation can help resolve a question. IN section 205.2 of the regulation, the definition of "account" is key: "a demand deposit (checking), savings, or other consumer asset account (other than an occasional or incidental credit balance in a credit plan) held directly or indirectly by a financial institution and established primarily for personal, family, or household purposes."

It is always helpful in the case of sole proprietorship accounts when the account documents state explicitly that the account is being opened for business purposes (or that it is NOT being opened for personal, family, or household purposes).

Which TIN is used is not relevant. It's the purpose of the account that matters.