Social Security: What Would Happen If the Trust Funds Ran Out? [Updated July 29, 2020] [open pdf - 1MB]
From the Introduction: "This report explains what the Social Security trust funds are and how they work. It describes the historical operations of the trust funds and the Social Security trustees' projections of future operations. It explains what could happen if Congress allowed the trust funds to run out. It also analyzes two scenarios that assume Congress waits until the moment of insolvency to act, showing the magnitude of benefit cuts or tax increases needed and how such changes would affect beneficiaries."
CRS Report for Congress, RL33514
Congressional Research Service: https://crsreports.congress.gov/