16 CFR 600 - The old FCRA commentary that has yet to be rescinded:
5. Information on an Applicant's Spouse
A. Permissible purpose. A creditor may request any information concerning an applicant's spouse if that spouse will be permitted to use the account or will be contractually liable upon the account, or the applicant is relying on the spouse's income as a basis for repayment of the credit requested. A creditor may request any information concerning an applicant's spouse if (1) the state law doctrine of necessaries applies to the transaction, or (2) the applicant resides in a community property state, or (3) the property upon which the applicant is relying as a basis for repayment of the credit requested is located in such a state, or (4) the applicant is acting as the agent of the nonapplicant spouse.
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