Tunisian lawyers wear a red armband during lawyer s sit-in protest against the new finance law, in front of the Tunis court, on January 5, 2023. AFP
Led by Bar Association head Hatem Mziou, lawyers gathered outside the Palais de Justice in Tunis as well as other sites, after the association called for a "day of rage".
The budget, unveiled last week, imposes new taxes to claw the North African country's deficit back to nearly five percent of GDP, as it awaits an international bailout.
Among the measures are a hike in taxes on legal fees, from 13 to 19 percent.
The Bar Association says its 9,200 members will only be liable for the new, higher rate when it is actually paid -- along with their fees -- by their clients.
It has also pointed out that the tax will hit legal service users from disadvantaged backgrounds hardest.
Mziou said in a speech that the new law "will help make citizens even poorer".
He also said Tunisian lawyers "will not stay idle in the face of attacks on rights and liberties".
He cited a controversial September decree by President Kais Saied which provides for jail terms against people found guilty of spreading false rumors "in order to undermine public security".
A lawyer who is defending a group of judges sacked by Saied said earlier this week that he is facing an investigation under the law.
On Wednesday evening, President Saied told Interior Minister Taoufik Charfeddine that "freedom doesn't mean chaos and plotting against the state", according to a statement from Saied's office.
Without naming anyone, he accused "certain people supported by known lobbies" of "violating the law and undermining national security".