Penske replaced Castroneves with Will Power for the upcoming IndyCar pre-season, and possibly some of the regular season.
Castroneves awaits a March 2 trial in Miami on charges he failed to pay around $5 million in federal taxes.
The driver told the Miami Herald that bringing Power in was best for everyone and that he was "very confident" he would be back racing soon.
The Herald said Wednesday that Castroneves could resume racing once the season begins April 5.
Penske President Tim Cindric said he was ready to welcome his top driver back.
"The easy thing in this situation might be to say, `Hey in 2010, Helio, we'll talk about it then' and just get on with 2009. But we didn't feel like that's the right thing to do," Cindric said.