Both former PwC Luxembourg employees stood trial in Luxembourg in 2016 for leaking confidential information about Luxembourg’s tax rulings set up by PwC to the press.
Charges included theft, disclosing confidential information and trade secrets, money laundering and fraud.
Deltour received a 12-month suspended sentence, which was later lowered to 6 months, and €1,500 fine.
Halet, meanwhile, landed a nine-month suspended sentence, which was later repealed, and a €1,000 fine.
The prosecution of the two whistleblowers has faced heavy criticism since the leaks later prompted a European crackdown on tax avoidance. On 3 June 2015, Antoine Deltour was awarded the European Citizens' Prize by the European Parliament.
The pair will challenge the verdicts against them, on the grounds that they acted honestly. If the appeal fails, they could take the case to the European Court of Human Rights.