Economic institute IAW said its study, published on the French website Challenges.fr, found undeclared income accounts for 9.9 percent of France's gross domestic product, compared to 13.2 percent in Germany and 13.9 percent in Sweden, The Local.fr reported Friday.
Friedrich Schneider, co-author of the study, credited the French system, which has stricter controls against cheating, with keeping taxes efficient.
"Taxpayers here are given incentives to not resort to black-market work," he said.
The study, which looked at 21 countries, indicates the most tax cheating is done in Greece -- where undeclared income represents 24.6 of the GDP -- and the least is done in the United States, where cheating represents 6.6 percent of the GDP.
Celebrity Families of 2014 [PHOTOS]