"Building on a similar feature of the MAP-21 highway bill passed in 2012, the House Ways and Means Committee proposal would allow corporations a range of rates for calculating defined benefit plan liabilities... The most generous funding calculation, which ended with 2012 plan years, would now be available to sponsors through 2017. The reduced pension funding contributions resulting from the change would bring in an estimated total of $6.4 billion in tax revenue, according to a [JCT] estimate ... Groups representing corporations also welcomed the absence of further premium increases for the [PBGC], which had been considered in earlier proposals."