Teachers can expect another fee hike for compulsory membership of the General Teaching Council for Wales (GTCW) next year, a teachers' union warns.
NASUWT Cymru is calling for the body to be merged with England because it is not financially viable.
This follows a difficult few months for the Welsh arm of the council, which was set up in 2000 following devolution.
In September, the fee rose from Pounds 33 to Pounds 45 - higher than England - which sparked outrage. It has emerged that a Pounds 3 million fund, designated for teachers' training, had run out in six months.
The GTCW is self-financing, generating its income by charging teachers a registration fee.
But the rise - blamed on more professional conduct cases in Wales - has upset many who view it as a "tax on teachers".
Chris Keates, general secretary of NASUWT, said: "If the GTCW continues in its present form, the only way it will be sustained is by expecting teachers to pay even more out of their own pockets. That is simply not acceptable."
Rex Phillips, the union's Wales organiser, said: "Economies of scale demand that there should be one council operating across England and Wales. Teachers' pay and conditions already operate across England and Wales, so why can't the regulatory body?"
The union has always been strongly critical of the council, often isolating itself from Wales's other teachers' unions. No others backed its call to scrap the council, despite widespread concern.
The National Association of Head Teachers (NAHT) Cymru has been particularly critical of the council's increasingly "punitive" actions.
They bitterly complained about the treatment of Paul Davies, the headteacher who was struck off by the council following a conviction for dangerous driving, which left a man in a wheelchair and for which Mr Davies received a 15-month jail term.
He was reinstated as head of Cwmdare Primary in Aberdare after winning a High Court appeal against the council's ruling.
Iwan Guy, NAHT Cymru's acting director, said: "There needs to be some changes, but we don't want to go in with England - our systems are too different."
UCAC, the Welsh medium teachers' union, also strongly criticised the council earlier this year for straying outside its remit. But it said it wanted to work with it, not see it abolished.
Dr Philip Dixon, of the Association of Teachers and Lecturers Cymru, said the call for a merged teaching council failed to take into account the realities of devolution.
Mal Davies, chairman of GTCW, said there was "nothing new" in the NASUWT's comments, and that there is a clear desire for a separate professional body in Wales.
"The Council is committed to managing its budget and costs effectively, seeking always to achieve excellent value for money and to represent the teaching profession in Wales in a proactive and independent manner," he added.