Their tables show the payroll tax is progressive thru the fourth quintile (they don't show deciles) for all taxpayers.
Also amusing is CTJ's response to the Tax Foundation's "Tax Freedom Day" idiocy.
Turns out that for the middle quintile of taxpayers, "Tax Freedom Day" (the day their income accumulates sufficiently to offset their imputed annual income tax liability) is January 21.
The piece is not up on their web site yet, but it should be any time now: http://www.ctj.org
mbs