Answer: Every tenant has a right to privacy guaranteed by the state Constitution. This right applies to a tenant's personal financial information. However, California Civil Code Section 1950.6 creates an exception to this privacy right to allow a landlord to conduct credit checks to screen rental applicants.
The purpose of this exception is to provide a fair opportunity to screen potential tenants. In your case, the landlord has already signed a lease, so the policy of encouraging adequate screening no longer applies. The landlord now has a binding contract with you, and with your wife, which means there is no longer a valid reason to violate your wife's right to privacy.
Even if the lease has a clause specifically permitting follow-up credit checks, the validity of that clause would be questionable in light of the right to privacy, especially because every credit check results in a "hard hit," which damages the person's credit score. If the clause has any validity, it could be invoked only if there were a relevant financial responsibility issue, such as your request to renegotiate your rent or some other lease terms. Otherwise, you and your wife have a binding agreement to the rental premises for the term of the lease.
If the landlord now tries to back out because your wife refuses to provide her financial information, you cannot force her to allow you to occupy the property. However, you would have a right to seek your damages for losing this rental opportunity, particularly because you have lost your current tenancy.
Eichner is director of Housing Counseling Programs for Project Sentinel, a nonprofit agency providing tenant-landlord and fair housing counseling in four Bay Area counties. To submit a question, contact firstname.lastname@example.org.