The Office of Thrift Supervision’s western regional director, Darrel W. Dochow, allowed IndyMac Bank to receive $18 million from its parent company on May 9 but to book the money as having arrived on March 31, according to the Treasury Department’s inspector general, Eric M. Thorson. The backdated capital infusion allowed IndyMac to plug a hole that its auditors had belatedly found in the bank’s financial results for the first quarter. If IndyMac had not been able to plug that hole retroactively, its reserves would have slipped below the minimum level that regulators require for classifying banks as well capitalized.

Though the $18 million transaction was minuscule in comparison to IndyMac’s $32 billion in assets, it had tremendous significance. If IndyMac had lost its well-capitalized status it would not have been allowed to accept “brokered deposits” from other financial institutions. Brokered deposits are typically high-yielding certificates of deposit arranged by brokers and sold to savings and loans. IndyMac relied heavily on brokered deposits, which amounted to $6.8 billion or 37 percent of its total deposits last spring.

“This is very significant in terms of whether IndyMac was over or under the O.T.S.’s thresholds for capital,” said Bert Ely, a veteran banking analysts in Alexandria, Va. “But what’s really troubling is that it seems to have been going on elsewhere.”

The episode had a link to the savings-and-loan scandals of the late 1980s, which cost the federal government more than $100 billion.

Mr. Dochow played a central role in the savings-and-loan scandal of the 1980s, overriding a recommendation by federal bank examiners in San Francisco to seize Lincoln Savings, the giant savings and loan owned by Charles Keating. Lincoln became one of the biggest institutions to collapse. Mr. Keating served four and a half years in prison before his fraud and racketeering convictions were overturned. He later pleaded guilty to more limited charges, and was sentenced to the time already served.