The U.S. Treasury Department issued proposed guidance on eligible Trump Account investments Thursday, establishing a framework for what products could qualify as additional investment options going forward.

The new tax-deferred investing accounts for children, also known as 530A accounts, are designed to jump-start long-term savings.

Under the proposed guidance, an eligible index must be designed primarily to measure the performance of a broad segment of the U.S. or global equity market using objective financial criteria, according to the Treasury Department. The guidance also limits eligible investments to those with low expense ratios, among other qualifiers.

"By emphasizing straightforward, low-cost investment options, the proposed guidance would allow children to benefit more fully from decades of compound growth and ensure that a greater share of investment returns remain in their accounts," the release said.

"Every dollar in a child's Trump Account should be working toward that child's financial future, not diminished by unnecessary fees," Treasury Secretary Scott Bessent said in a statement. "Under President Trump's leadership, Treasury is putting simple, commonsense protections in place to help families keep more of their investment returns."

Bank of New York Mellon is the official manager for newly created Trump Accounts. The proposed guidelines also apply to future Trump Account trustees, should a family decide to transfer their assets to a new custodian.

Currently, contributions to Trump Accounts are invested in exchange-traded funds that track the performance of the S&P 500.

Treasury previously announced that State Street SPDR Portfolio S&P 500 ETF (SPYM) would be the default investment at the outset.

The other investment options include the iShares Core S&P 500 ETF (IVV); the Vanguard Total Stock Market ETF (VTI); the State Street SPDR Portfolio S&P 1500 Composite Stock Market ETF (SPTM); and the iShares Core S&P Total U.S. Stock Market ETF (ITOT).

"For a child investing over decades, even small differences in annual costs may have a meaningful effect on the amount available in adulthood," Frank Bisignano, CEO of the IRS, also said in the release. "By emphasizing low-cost index investing, the proposed rules seek to maximize the share of investment returns that remains in each child's account."

After opening an account, families can track account activity in the Trump Accounts app, which was designed in partnership with Robinhood.

"We wanted to make it as easy as possible for every American starting at birth to get access to the great American economy, to get ownership of these companies from birth and see the magic of compound interest," Robinhood CEO Vlad Tenev said Wednesday on CNBC's "Squawk Box."

"Over time, there's been discussion about more [investment] options, but I think the default of a diversified portfolio of the most prominent companies has been a great way to start and has been very effective," Tenev said.