Austria's ruling coalition of three centrist parties proposed the ban in schools, arguing it was acting to protect girls' freedom. The legislation was passed in parliament in December with the support of the far-right Freedom Party. Only the smallest party in parliament, the left-wing Greens, opposed it.
The group that formally represents Austria's Muslims, the Islamic Religious Community in Austria (IGGO), has said the move was an infringement of fundamental rights, pledging to fight it before the Constitutional Court, which rejected challenges in July because the legislation had not yet gone into force.
The court ruled in 2020 that a previous ban, which applied to under-10s in schools, was illegal because it discriminated against Muslims and the state had a duty to be religiously neutral. Going against that principle requires special justification, it held.
Asked by national broadcaster ORF if the court would overturn the new ban, Education Minister Christoph Wiederkehr said: "You can never be completely certain."
"We in the government carried out very intensive consultations and we in the education ministry tried very hard to write a law that complies with the constitution," Wiederkehr said.
Left-wing pupils' organisations have called for protests. The new school year starts on Monday in three of Austria's nine states - Vienna, the surrounding state of Lower Austria, and Burgenland, all in the east - with the rest following next week.
The legislation stipulates a school must hold discussions with any pupil defying the ban, after which a fine of between 150 and 800 euros ($A243 to $A1290) can be imposed.
