(a) The monthly CPI-U values needed for the calculation of the partial year limitation under this section shall be obtained from the Bureau of Labor Statistics (BLS) Consumer Price Index—All Urban Consumers, U.S. All Items, Not Seasonally Adjusted, Base Period 1982 − 84 = 100. The current Series ID for the index is “CUUR0000SA0.”

(b) If a notice of a Type 1-A or Type 1-B rate adjustment is filed less than 12 months after the most recent Type 1-A or Type 1-B notice of rate adjustment, then the annual limitation for the class (referred to as the partial year limitation) will recognize the rate increases that have occurred during the preceding 12 months. When the effects of those increases are removed, the remaining partial year limitation is the applicable restriction on rate increases.

(c) The applicable partial year limitation is calculated in two steps. First, a simple average CPI-U index is calculated by summing the 12 most recently available monthly CPI-U values from the date the Postal Service files its notice of rate adjustment and dividing the sum by 12 (Recent Average). The partial year limitation is then calculated by dividing the Recent Average by the Recent Average from the most recent previous notice of rate adjustment (Previous Recent Average) applicable to each affected class of mail and subtracting 1 from the quotient. The result is expressed as a percentage, rounded to three decimal places.

(d) The formula for calculating the partial year limitation for a notice of rate adjustment filed less than 12 months after the last notice is as follows: Partial Year Limitation = (Recent Average/Previous Recent Average) − 1.

[78 FR 52704, Aug. 26, 2013, as amended at 79 FR 33833, June 12, 2014. Redesignated at 85 FR 9615, Feb. 19, 2020]