The Fire Department has for years underreported the value of free commuting privileges it provides to some of its top officials, The Post has learned.

The IRS allows most employees to calculate the value of each ride at just $1.50 no matter how far they go.

But any worker earning $139,600 or more is bound by a different formula based on either the actual mileage or the mileage combined with the value of the vehicle.

Ignoring explicit instructions from the Office of Payroll Administration, fire officials added the same $660 as a fringe benefit to the pay stubs of everyone on its commuting list.