What you have to prove
Medical documentation of the disorder with at least five depression or bipolar symptoms, AND extreme limitation of one OR marked limitation of two of the four 'Paragraph B' functional areas (understand/apply info, interact, concentrate/persist, adapt); OR a serious and persistent disorder over 2+ years with marginal adjustment.
Medical evidence SSA expects
Psychiatrist and therapy records, medication trials and responses, hospitalization records, mood charts, and third-party statements documenting functional impact at home and in social settings.
Common misconceptions
Depression that's responsive to medication and therapy is rarely approved at the listing level. Many applicants win on appeal by documenting treatment-resistant cases or by combining mental and physical limitations in a Medical-Vocational Allowance.