Nursing home said they needed my dads SSN for billing reports even though they had his MBI. Does CMS require this?

They should not need his social security as the MBI is his identifier.

I know for Medicaid the SSN is needed. Medicare's new ID# should be enough. Call CMS and see if it is a requirement. If person is already on Medicaid call the caseworker. Medicaid recipients do have their own case#s.