Michael Hiltzik: The chained CPI is another secret tax hike for the middle class slipped into the GOP tax bills

The devastating effect that many provisions of the Republican Senate and House tax bills would have on the middle class have been well documented, thanks to the efforts of independent analysts at the Tax Policy Center and elsewhere.

But here's a tax increase on working Americans that hasn't been very well publicized, even though it's in both GOP proposals. It's a change in the inflation measure on which tax rates are calculated to something called the chained consumer price index.

I've written about the chained CPI many times in the past, generally when it's been put forth as a new way to calculate cost-of-living adjustments for Social Security. In that context, it's a stealth benefit cut. Up to now, it has always been rejected - most recently in 2013, when President