Peter Altmaier, German Chancellor Angela Merkel's chief of staff, will take over as acting finance minister from Wolfgang Schaeuble when he leaves office, German newspaper Sueddeutsche Zeitung reported on Friday.
It said, without citing its sources, that Merkel had made the decision.
On Wednesday 75-year-old veteran conservative Schaeuble agreed to become president of the parliament in a move seen as a key step towards forming a new government because it ultimately clears the way for someone from another party to take his job.
Merkel's conservatives, who won a national election on Sunday, look set to try and form a coalition with the pro-business Free Democrats and environmentalist Greens after the Social Democrats (SPD) said they would go into opposition.
Schaeuble is due to be nominated as the conservatives' candidate for president of the parliament at the next meeting of the conservatives' parliamentary group on Oct. 17.