Geithner told a congressional panel charged with oversight of the bank bailout that there is $109.6 billion remaining of a $700 billion bailout package, with an additional $25 billion expected to be returned over the next year. That would bring the available funds to $134.6 billion.

Already, six smaller banks have returned capital they received from the Troubled Asset Relief Program, known as TARP. Moreover, both Goldman Sachs and J.P. Morgan & Chase have said recently that they are seeking to return $10 billion and $25 billion, respectively.

In a table provided to the panel, the Treasury Department says that the $25 billion it expects to be repaid is a conservative estimate.

However, Geithner indicated that he and other bank regulators may not immediately accept funds from participating banks seeking to return it. Geithner said the Treasury, the Federal Reserve and the Office of Comptroller of the Currency are considering both the viability of each financial institution and the economy “as a whole” before deciding whether to let financial institutions return the funds.

“The institutions are in different circumstances,” Geithner said. “My basic obligation is to make sure that our system as a whole has an ability to recover.”

Regulators, he told the panel, are working against two questions: whether institutions themselves have enough capital and whether the system as a whole is working.

On what has become a topic of keen scrutiny, Geithner declined to comment about details of “stress tests” that the Treasury and bank regulators are conducting for the 19 largest U.S. banks that have received bailout funds.

Based on what the test findings — which are expected on or around May 4 — show, bank regulators may take steps to hike the common shareholdings of troubled financial institutions, including the conversion of billions in government preferred shares into common shares.

Congressional oversight panel member John Sununu, a former senator from New Hampshire, said that disclosure of the results of these tests could hurt the viability of the financial institutions.

“Why would you disclose this information when bank regulators have in the past kept this kind of information confidential?” Sununu asked.

Geithner said he believes transparency is critical for the program, which is being conducted by the Fed and the OCC.

“I do believe it is valuable to bring more disclosure about potential losses,” Geithner said. “Transparency will be helpful.”

Geithner also responded to concerns about how the program may convert billions of preferred shares the government owns in the largest banks into common shares.

Panel member Damon Silvers asked how taxpayers are protected if the government owns common shares instead of preferred shares, which are protected more heavily in bankruptcy proceedings.

Geithner said the banks must look to the private sector first for capital before the government considers any preferred-to-common conversion.

“We want to make sure the capital the system requires is targeted where needed,” Geithner said. “It’s designed to make clear that there is clarity.”

At the same time as Geithner was testifying before the congressional panel, TARP inspector general Neil Barofsky released a report offering recommendations for the program.