Default Prevention Act - Requires the following to be granted priority over all other federally incurred obligations in the event that the public debt reaches the statutory limit: (1) the authority of the Department of the Treasury to pay with legal tender the principal and interest on debt held by the public; (2) the full payment of compensation, allowances, and benefits for members of the Armed Forces on active duty, (3) the authority of the Commissioner of Social Security to pay monthly Old Age, Survivors and Disability Insurance benefits under title II of the Social Security Act (SSA); and (4) the authority of the Secretary of Health and Human Services (HHS) to make payments for items and services furnished to beneficiaries under SSA title XVIII (Medicare) and related provisions.