As many as 35 councils in England have changed their policy on fining parents for taking children out of school for holidays in term-time.
It follows a successful high court appeal by a father last year against a £120 fine levied by Isle of Wight council.
The case goes to the Supreme Court tomorrow where judges will consider what constitutes regular attendance. Ministers argue missing days at school has an impact on pupils’ exams.
Most parents simply pay the fines issued for unauthorised absence from school to avoid prosecution.
But businessman Jon Platt refused after facing prosecution for taking his daughter out of school for a term-time holiday Disney World in Florida in 2015.
He has argued that her attendance was regular because even after the holiday it was over the 90% threshold set out by the Isle of Wight in its policy. It was an argument that was accepted by the High Court.
The Supreme Court will consider the arguments on Tuesday but the judges are likely to take months before outlining their decision.
The BBC has gathered information from 108 councils and found 35 have changed their policy as a direct result of Platt’s case.
A further five are currently reviewing their guidelines and 28 have withdrawn fines issued to parents.
Of the councils that provided information, 22 told the BBC the number of parents taking term-time holidays has increased.
In North Somerset 100 fines have been put on hold while the council considers its policy.
And while Suffolk issued 6,008 fines in the 2015-16 school year there were just 108 on North Tyneside. Richmond upon Thames in London issued none in the same period.
Platt’s legal team will present evidence to the Supreme Court from more than 100 freedom of information requests to local councils.
It shows that some authorities have fined thousands of parents for unauthorised school absence, while others have fined none, The Sunday Times reported.
Lancashire has issued nearly 4,000 penalty fines since Platt won the High Court ruling in May that he did not have to pay.
But several councils have stopped issuing fines, including Bury, Dorset, Oldham, North Yorkshire and Staffordshire.
Cornwall has issued about a dozen fines but neighbouring Devon has issued thousands.
“When parents are prosecuted for refusing to pay the fine and can afford a solicitor who understands the law they are usually not being found guilty if their child’s attendance is more than 90%,” Platt told the newspaper.
“There is something telling about the areas that issue a lot of fines compared to those that issue few. It is a ridiculous postcode lottery. Is it a class issue?”