His decision to leave the administration this month and return to New York is pretty firm, now that the "fiscal cliff" showdown is over and President Barack Obama signed a bill to raise taxes on the wealthiest Americans, a source close to Geithner told Politico.
Geithner, 51, a key player in the cliff negotiations, had long planned to leave Washington after the cliff fight was over, the source said.
His wife Carole and son Benjamin moved back to New York in June 2011 so Benjamin could finish high school where he grew up.
Before moving to the Washington area, the Geithners lived in Larchmont, N.Y., while Geithner was president of the Federal Reserve Bank of New York.
Geithner is the last remaining member of Obama's original economic adviser team that shaped the president's response to the 2008 financial crisis.
His intention to leave the administration increases pressure on Obama to name a successor as Treasury secretary, Politico said.
White House Chief of Staff Jacob Lew, a former Office of Management and Budget director, remains the leading contender for the Treasury job, Politico and CNN reported.
"Secretary Geithner has previously stated that he plans to be at Treasury until around the inauguration," a Treasury representative said Thursday.
"We do not plan to make any further announcements about the timing of the secretary's departure until after his successor is named."
The fiscal cliff deal, part of which must still be negotiated before March, did nothing to raise the government's borrowing limit.
Geithner has said Congress must increase it within the next 10 weeks or so. Washington officially hit its current authorized borrowing limit of about $16.4 trillion Monday.
Geithner told Congress last week he would be able move money around to buy time, but only for a matter of weeks.
Congress periodically needs to raise the borrowing limit, or debt ceiling, if the government spends more than it takes in. The United States is running deficits of about $1 trillion a year.
The last time a similar debate occurred, in the summer of 2011, the talks turned nasty, the United States lost its triple-A credit rating with the Standard & Poor's rating agency and markets around the world experienced their most volatile week since the depths of the financial crisis.
In the coming debate, congressional Republicans have said they will continue to demand, as they did in 2011, that any debt-limit increase be tied to significant spending cuts.
But Obama said he would not negotiate over the limit this time.
"I will not have another debate with this Congress over whether or not they should pay the bills that they've already racked up through the laws that they passed," Obama said New Year's Day, as the House prepared to approve the fiscal-cliff deal.