Buried in the debate over tax breaks for the wealthiest Americans and unemployment benefits for those out of work is a measure that will affect the amount of money that thousands of public-transit riders spend to get to work.

Legislation to extend the commuter-tax benefit that allows riders to use pretax dollars for their transit fares must be passed by Dec. 31 to keep the benefit from diverting from $230 per month to the original $120 limit.

The benefit extension was included in the $858 billion tax package advanced yesterday by the Senate.

The bill was to come up for final approval in the Senate today and will then be taken up by the House.

Mantill Williams, director of advocacy communications for the American Public Transportation Association, said he expects that the bill will pass quickly with a final vote likely by Thursday.

"The commuter-benefit provision is currently in the bill and we hope it will be retained," Williams said. "The House will act on the overall bill and may make amendments to the overall bill but we expect the commuter benefit to remain intact."

Joanne Moroz, 44, travels through three zones on SEPTA's Regional Rail trains from her home in Hatfield, Montgomery County, to the Center City law office where she works.

She saves $186 annually on TrailPass costs and nearly $2,000 in end-of-the-year taxes using SEPTA's ComPass program.

Moroz would lose the ability to deduct all of her monthly $155 transit costs from her paycheck pretax if the benefit increase, enacted in the American Recovery and Reinvestment Act of 2009, is not extended as part of the tax package.

"We hear them say the economy is getting better, but for whom?" Moroz asked. "We need benefits like this to help us out. They shouldn't be taken away."

SEPTA, APTA and the Delaware Valley Regional Planning Commission have been urging commuters this month to contact lawmakers to ask them to support the extension.

All but one of SEPTA's monthly Regional Rail passes are priced above the old $120 pretax cap amount. Any commuter using a Zone 3 or higher TrailPass would be affected if the benefit is not extended.

On average, 14,000 riders purchase Zone 3 passes every month and nearly 5,000 riders purchase passes for Zone 4 and above each month, according to SEPTA.