Social Security Trust Fund Protection Act of 1985

Social Security Trust Fund Protection Act of 1985 - Directs the Secretary of the Treasury to issue public debt obligations to the Federal Old-Age and Survivors Insurance Trust Fund, Federal Disability Insurance Trust Fund, Federal Hospital Insurance Trust Fund, Federal Supplementary Medical Insurance Trust Fund, Railroad Retirement Account, Civil Service Retirement and Disability Fund, and Department of Defense Military Retirement Fund for such terms and at such interest rates as will ensure a projected annual interest income to such funds equivalent to the income which would have been earned by those funds from public debt obligations which: (1) were redeemed on or after September 1, 1985, and on or before the date of the enactment of this Act; and (2) would not have been redeemed had the public debt limit been raised pursuant to a specified resolution of the House of Representatives. Directs the Secretary to pay to the funds the interest which would have accrued to the funds but for such non-investments, redemptions, and disinvestments.

Amends title II (Old Age, Survivors and Disability Insurance) of the Social Security Act to require the Managing Trustee of the Federal Old-Age and Survivors Insurance Trust Fund and the Federal Disability Insurance trust fund (OASDI trust funds) to submit an advance report to the Board of Trustees of such trust funds and to each House of the Congress of the effects on the OASDI trust funds of reaching the public debt limit. Authorizes the Managing Trustee to disinvest either trust fund only to the extent necessary to prevent a shortfall in amounts available for benefit payments.

Restricts the authority of the Secretary of the Treasury to transfer specified tax revenues to the OASDI trust funds by requiring the Secretary to first determine that the balance in either trust fund would otherwise be insufficient to permit full payment of benefits for any month.