33 C.F.R. § 138.240
(b) Formula for calculating a cumulative percent change in the Annual CPI-U.
(1) The Director, NPFC, calculates the cumulative percent change in the Annual CPI-U from the year the limit of liability was established, or last adjusted by statute or regulation, whichever is later (i.e., the previous period), to the most recently published Annual CPI-U (i.e., the current period), using the following escalation formula:
Percent change in the Annual CPI-U = [(Annual CPI-U for Current Period−Annual CPI-U for Previous Period) ÷ Annual CPI-U for Previous Period] × 100.
(d) Formula for calculating inflation adjustments. The Director, NPFC, calculates adjustments to the limits of liability in § 138.230 for inflation using the following formula:
New limit of liability = Previous limit of liability + (Previous limit of liability × percent change in the Annual CPI-U calculated under paragraph (b) of this section), then rounded to the closest $100.