Chained Consumer Price Index: What is it and Would it be Appropriate for Cost-of-Living Adjustments? [June 12, 2013] [open pdf - 359KB]
"The U.S. Bureau of Labor Statistics (BLS) publishes two important measures of inflation: the Consumer Price Index for all Urban Consumers (CPI-U) and the Consumer Price Index for Urban Wage Earners and Clerical Workers (CPI-W). (Hereinafter in this report, the CPI-W and CPI-U will be referred to collectively as the standard CPI.) The standard CPI might seem like just another economic indicator, but it is a powerful policy lever. Because the CPI-W is used to calculate annual cost-of-living adjustments (COLAs) to Social Security retirement benefits and the CPI-U is used to calculate annual inflation adjustments to personal income tax brackets, for example, changing the basis of the adjustments could substantially affect outlays and revenues. Since August 2002, BLS has published a supplemental measure known as the Chained Consumer Price Index for all Urban Consumers (C-CPI-U). The aim of the C-CPI-U is to produce a measure of change in consumer prices that is free of substitution bias. One of the difficulties in estimating cost-of-living changes is that consumers often alter their buying patterns in response to changing relative prices. In other words, consumers tend to buy more of the goods and services whose prices are rising slower than average and fewer of the goods and services whose prices are rising faster than average. Substitution is believed to insulate consumers from the full effect of rising prices on maintaining their standard of living. Because the CPI-W and CPI-U do not entirely account for substitution, they overstate the impact of inflation on consumer well-being. As a result of better reflecting consumer substitution, the C-CPI-U has typically increased to a lesser extent than either the CPI-U or CPI-W. This relationship has prompted calls for switching to the C-CPI-U when calculating automatic adjustments to inflation-indexed federal programs and individual tax provisions to slow growth in the budget deficit. The 2010 'Simpson-Bowles' report recommended government-wide replacement of the CPI-W and CPI-U with the chained CPI, for example. In April 2013, a modified version of the Chained CPI-U proposal was included in President Obama's Fiscal Year 2014 Budget."
CRS Report for Congress, RL32293