If a popular piece of retirement legislation makes it to President Biden's desk this year, it would give older 401(k) participants the opportunity to contribute more to their nest egg and possibly bolster their tax-free savings.

Currently, anyone 50 or older may contribute an additional $6,500 on top of the annual $20,500 federal 401(k) contribution limit, for a total of $27,000 a year.

But under the Secure Act 2.0, which the House passed in March, the cap on catch-up contributions would increase to $10,000 for people ages 62, 63 and 64. So they'd be allowed to save a total of $30,500 in their 401(k)s.

A similar bill under consideration in the Senate would allow the catch-up contribution limit to increase to $10,000 for anyone 60 and older.

But there's another element in the House bill that would affect anyone who decides to make catch-up contributions from age 50 and up. The legislation would "Rothify" them. So instead of putting your catch-up contribution into a traditional 401(k) account and getting a tax deduction for it, it would be deposited into a Roth 401(k) account and you would have to pay income tax on your contribution the year you make it. In exchange, that money you invest would grow tax-free, and any distributions you take from that Roth account in retirement would also be tax free income to you.