Castroneves - who sold his Coral Gables mansion last year and moved into a Fort Lauderdale waterfront rental apartment with his wife and daughter - is contesting the IRS claims.
Since his peak days in IRL and IndyCar last decade, Helio has been finding success harder to come by on the race track. In the last 18 months he has been increasingly overshadowed at Penske by the success of his Australian team mate Will Power, who came close to winning the 2010 IndyCar championship after a string of road course wins.
Castroneves did take three race wins in 2010 but is winless so far in 2011, while Power has won twice at Alabama and Sao Paulo. Power tops the IndyCar championship on 168pts while Helio is exactly a hundred points behind in a lowly 17th position. It's a season that has seen him become worryingly accident-prone, including taking his team mate out of a potential race win with an on-track collision at Long Beach.
Ironically, Power's own involvement with Penske Racing dates back to 2009, when the team needed a driver to fill in while Helio was facing his original tax trial.
Helio remains one of IndyCar's biggest star names in the US, not just thanks to his success in the sport and at Indianapolis, but because of his win in the celebrity reality show "Dancing with the Stars" which made him a familiar face and personality across America beyond just motor sports circles. His flamboyant habit of climbing the wire fencing surrounding oval tracks to salute the crowds after a race has also boosted his popularity and fame, and won him the nickname of "Spider-Man".
This month, the Brazilian star - who turned 36 on Tuesday, May 10 - is aiming to become the first four-time Indy 500 winner born outside of the USA, following in the footsteps of AJ Foyt, Rick Mears and Al Unser.
Meanwhile, long-time rival Dario Franchitti will be aiming to join Helio on the three-win step and become only the second foreign-born driver to reach that Indy 500 landmark.