A congressional debate on a bill to reform Social Security has turned to a key question: whether changes made to the system today will upend millennials' retirement in the future.

A committee hearing of the House Ways and Means Committee on Thursday focused on the potential impact of the Social Security 2100 Act. That bill, put forward by Rep. John Larson, D-Conn., earlier this year, is aimed at expanding the solvency of the program for the rest of this century while expanding benefits for retirees and other beneficiaries.

Social Security's trust funds are currently projected to be depleted in 2035, at which point only 80% of estimated benefits will be payable. Today's retirees receive an average of $17,000 per year in benefits.

The Social Security 2100 Act aims to shore up the system by raising payroll taxes on wages over $400,000. Only wages up to $132,900 are currently taxed.

The plan also proposes increasing payroll contributions from both workers and employers. That rate would increase to 7.4% from 6.2% and would be gradually phased in from 2020 to 2043.

Those changes would help pay for the plan's benefit increases, including give those who are or will be receiving benefits a raise equal to 2% of the average benefit.

But Congressional Democrats and Republicans are divided as to whether this latest proposal will help or hurt Americans' future retirement.

"I often hear from constituents who wonder if Social Security will still be there for them when they need it," said Rep. Richard Neal, D-Mass., chairman of the House Ways and Means Committee. "And our constituents want us to strengthen it, not cut it.

"And that's what the Social Security 2100 Act does," he added.