The former EastEnders actor welcomed the arrival of his first child Harry in June 2007, but he split from the baby's mother Emma Sophocleous just seven months later. Sophocleous later accused the star of leaving her "totally in the lurch".
According to the News Of The World, the CSA - now called the Child Maintenance Enforcement Commission (CMEC) - had started investigating the matter when Swash took part in I'm A Celebrity, Get Me Out Of Here! in November. He went on to win the series, triumphing over Martina Navratilova and George Takei.
"Emma said she was now getting £60 a week, but wasn't all that pleased about the amount," a source told the newspaper. "She reckons Joe has made much more than that from all the deals he's done since being crowned king of the jungle."
A spokesman for Swash explained: "He is abiding by the CSA ruling and will continue to do so in the future. It has been a difficult relationship with his son's mother and he and his lawyers are working on a solution with regards to access to his son that will suit everyone."