Shamima Begum was granted legal aid to fight against the Home Office's decision to remove her citizenship.
Lawyers for the bride of Isis have reportedly been rewarded with taxpayers' money and are preparing to appeal against the decision of Interior Minister Sajid Javid to revoke citizenship.
Taxpayers face a bill that could amount to hundreds of thousands of pounds, according to the Daily Mail.
This happened after it emerged that Begum, 19, had "put suicide bombers in the West and carried on a ruse" while she was a member of a "dreaded moral police" in Syria.
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Javid said he had deprived Begum, who fled to Syria at the age of 15, of his citizenship in order to "protect his country."
Although Begum is no longer a British citizen, there are legal stipulations under which funds should be available if the case is brought before a British court.
The money requested by their lawyers, not by Begum or their family, is used to pay for the return of their court battles.
The Legal Aid Agency (LAA) has accepted that their lawyers can file applications on their behalf, even though they can not speak in the refugee camp where they live in Syria.
Begum itself will not be able to take part in the case that the Special Immigration Appeals Commission decides to prohibit returning to the United Kingdom.
The LAA's decision was met by a backlash, and Tory's MP Philip Davies said funding for a person who has left Britain to join the extremist group is "repugnant."
Tory's deputy Tim Loughton accused Begum of "playing the victim card".
The Home Office said that they did not comment on individual cases, but added: "Any decision to deprive citizens of their citizenship is based on all available evidence and is not taken lightly."
The LAA also refused to comment on individual cases, but said: "Anyone seeking legal assistance in a Special Immigration Appeal Commission case is subject to rigorous proficiency checks."
A spokesman for the Interior Ministry said, "To protect this country, (the Home Secretary) has the power to rob someone of his British citizenship if he does not make them stateless.
"We do not comment on individual cases, but any decisions to deprive people of their citizenship are based on all available evidence and are not taken lightly."
The family lawyer, Tasnime Akunjee, confirmed the legal aid and said the case had been referred to renowned human rights lawyer Gareth Peirce, who represented former prisoner at Guantanamo Bay, Moazzam Begg.
Akunjee told Daily Mail, "I represent the family who originally filed the case on behalf of Shamima Begum, but the family is not eligible for legal aid – legal aid is only for Shamima Begum."
Begum disappeared in 2015 and reappeared in al-Hawl refugee camp in February this year.
Begum was one of three students in London who fled to Syria. The other two are feared dead.
She was then in the third phase of her third pregnancy and had already lost two children to malnutrition.
The regime's last major territorial stronghold collapsed last month and dozens of British citizens are now stuck in Syria.