Kerviel was initially ordered to repay the whole sum, but subsequent rulings had struck down that decision. In June, a public prosecutor said the bank "had left the door open" for Kerviel to act illegally.
Earlier today, French junior budget minister Christian Eckert told Europe 1 radio: "We will act on the court judgements as soon as we know what they are."
A lawyer for SocGen said the bank had "no worries" over the tax deduction.
The former trader has always admitted making the unauthorised trades, arguing that the bank turned a blind eye when they went well, but turned against him when they didn’t.
In 2010, Kerviel was sentenced to three years in prison after being convicted of breach of trust and fraud over the huge losses from equity derivatives trades in 2008. He lost a subsequent appeal against the sentence.
However, in 2014, he was freed after just five months in prison. At the time, his lawyer David Koubbi said Kerviel had found a new job in IT and would keep fighting Societe Generale, who he said had made him a scapegoat.