Tauranga Budget Advisory manager Diane Bruin said the new fares would impact "hugely" on clients.
In some family budgets - which could change seasonally - every dollar was accounted for and they would struggle to find an extra $11.50 per child.
"For a lot of them there's hardly room to move," she said.
A lot of parents drip-fed $5 or $10 to their child's school each week to cover fees, camps, stationery and uniforms, but couldn't afford to pay the same again.
"School is an absolute necessity for the children; they need that education so they have better opportunities when they get older."
Paying for school buses did not reflect a free education, she said. "I know we all have to pay our part of it but I don't know where it ends."
Mrs Bruin also predicated the change would see more parents driving their children to and from school.
"We're trying to reduce pollution and footprints so is that really a good idea?"
Welcome Bay mother-of-eight Sai Watson-Crooks moved suburbs late last year, expecting to be able to send two of her children to Tauranga Boys' College and Tauranga Intermediate free of charge.
Despite being at a rural address, their Waikite Rd home is not considered rural when it comes to school buses.
"We struggle at the best of times with eight kids," she said.
"The whole point of it is that it's supposed to be free schooling, there's nothing free about it. It's getting harder and harder for everybody to keep our kids at school," she said.
"We shouldn't have to pay for kids to go to the closest school for them - which is miles away."
As a self-employed couple their income varied depending on the time of year but Mrs Watson-Crooks had no idea how couples on benefits would manage.
"There's going to be so many kids not going to school," she said. "There are a lot of families that don't have that money and they don't have cars."
She suggested schools incorporate a bus charge into their compulsory fees, which could be paid off throughout the year.
Yearly cost of getting three to school - $1300
By next year Papamoa mother-of-three Jackie Davison will be facing an annual school bus bill of more than $1300.
Next term the family will pay at least $4.60 a day to get two children to school, rising to $6.90 when their youngest starts Intermediate next year.
"For a free education there's just so many extra costs with schools it's not even funny. It makes it very hard for people. If they didn't tag it to be the free education system it wouldn't hurt so much," Mrs Davison told the Bay of Plenty Times.
The family was paying $25 a term to send one child to Mount Maunganui Intermediate - which they were happy to do because it was not the nearest option to their Santa Barbara Drive home.
Now they have to pay $2.30 a day for the same child to attend school and the same amount for their eldest daughter to attend Mount Maunganui College - despite living closer to Papamoa College but one street out of zone. Up until this year, the bus to Mount College - the nearest in-zone school - had been free.
Mrs Davison said the Ministry of Education should continue to provide free bus transport for those attending their nearest in-zone school, while charging those who had forgone a closer option.
"They choose to not allow our children to go to Papamoa College."
The cycle route from Papamoa to Mount College was unsafe,
"It's just an accident waiting to happen. I don't think it's particularly safe to have kids biking down there at that time of day.
"To take them down to the Mount (in the car) and then come back in the morning is just hideous. It is actually quite convenient putting them on the bus."
Cycling to Papamoa College could be an option, were her daughter allowed to attend.
