IF YOU drive to work, expect a boost next year in the monthly parking benefit available through a federal tax break. But if you take the bus, train or subway — transportation that government generally encourages people to use — forget about getting any extra help. In fact, you’d better steel yourself for a big cut in benefits.

It’s a paradox of public policy that (no surprise) comes courtesy of a Congress that doesn’t seem to realize, or much care about, the consequences of not doing its job.

One of the things lawmakers failed to do before adjourning this year, The Post’s Jia Lynn Yang reported, was adjust the program that allows workers, through their employers, to set aside pretax income to offset the cost of their commutes. As a result, starting Jan. 1, commuters who use mass transit will be able to set aside only $130 a month, down from $245 a month, while drivers will be able to increase their monthly parking set-aside from $245 to $250. Never mind that the increased use of public transportation benefits everyone, including those who continue to drive, giving them less traffic to contend with.

The nonsense of giving bigger subsidies to drivers is embedded in the program’s start in the 1990s. Parity for mass-transit users was established in 2009, but the fix, unfortunately, was never made permanent. Hence the current dilemma that will most affect heavy users of transit in big cities. In the Washington area, Metro officials are already envisioning fewer riders if federal workers and other commuters don’t think it is worth their while to pay more. And even if lawmakers, as some promise, act early in the year to adjust the program, there will still be a lag before the change kicks in.

Perhaps there is an argument to be made about whether the federal government wants to continue to be in the business of helping workers pay for their commutes. But there can be no good argument for giving an edge to drivers and less incentive for people who use far more beneficial public transportation.