Effective from its commencing date, an annuity payable from the Fund to an annuitant’s survivor (except a child entitled under
section 8341(e) of this title), which annuity commences the day after the death of the annuitant and after the effective date of the first increase under this section, shall be increased by the total percent increase the annuitant was receiving under this section at death. However, the increase in a survivor annuity authorized by
[section 8 of the Act of May 29, 1930], as amended to
July 6, 1950, shall be computed as if the annuity commencing date had been the effective date of the first increase under this section.