The fund was criticized by opposition legislators, who said the ruling party had earlier claimed the government was broke, Tunisia Live reported Monday.
The Dignity and Rehabilitation for Victims of Tyranny Fund was passed in the National Constituent Assembly by a vote of 87-13 as part of the government's 2014 finance appropriation. Nineteen members abstained.
Members of the ruling Ennahdha party said the law would "guarantee the compensation rights of victims of tyranny."
The government had previously told the assembly "there is no money, and that the treasury is empty," said Iyed Dahmani, a member of the opposition al-Joumhouri party.
"We were surprised by the end of the night as there was money to create a fund."
Ben Ali fled Tunisia in January 2011 at the beginning of the Arab Spring revolution.