; and proper adjustments shall be made in amounts subsequently transferred to the extent prior estimates were in excess of or were less than the taxes specified in such paragraphs. All amounts transferred to the Social Security Trust Fund under the preceding sentence shall be invested by the Managing Trustee in the same manner and to the same extent as the other assets of the Trust Fund. Notwithstanding the preceding sentence, in any case in which the Secretary of the Treasury determines that the assets of the Trust Fund would otherwise be inadequate to meet the Trust Fund's obligations for any month, the Secretary of the Treasury shall transfer to the Trust Fund on the first day of such month the total amount which would have been transferred to the Trust Fund under this section as in effect on October 1, 1990