The biggest teaching union in Wales has accused the Assembly government of trying to water down schools' obligation to review their staffing structures.
Draft guidance on how Welsh head and governors should replace management allowances with new teaching and learning responsibility payments (TLRs) is "totally unacceptable", according to NASUWT Cymru.
It accuses the Assembly government of modifying the guidance already published in England to imply there is no obligation on schools to change their staffing structures to accommodate TLRs.
It has told the Assembly government it should attend meetings of the London-based group that developed TLRs "to avoid any future misunderstandings".
TLRs were proposed by the rewards and incentives group (RIG), a consultative group of signatories to the 2003 workload deal.
Geraint Davies, secretary of NASUWT Cymru, said: "The Assembly government has not been attending RIG meetings, and we think that has been to the detriment of teachers in Wales. They could be disenfranchised as they will not be properly represented, outside the trade unions, in those important bodies."
Management allowances, held by thousands of teachers in Wales and England, end on December 31, although existing payments will be safeguarded for three years.
Schools have to review their staffing structures and decide how many TLRs to award and for which responsibilities. Schools in England have until December 31 to come up with their new plans, with a deadline in Wales of March 31.
An Assembly government spokesperson said officials had always been willing to attend RIG meetings where this would be helpful, and would do so more regularly in future.
The deadline for staff reviews was extended after public consultation, and would ensure Welsh schools have the same lead-in time as those in England, she said.
The NASUWT wants Welsh schools to work to the English deadline to avoid confusion. But its classroom rival, the National Union of Teachers Cymru, is urging Welsh schools to resist pressure to rush staff reviews.
The union also wants an extension to the three-year transition period for introducing TLRs in all schools.
Gethin Lewis, secretary of NUT Cymru, which opposes TLRs, said encouraging Welsh schools to work to the English deadline was "flying in the face of devolution".
He added: "That extra term for staff reviews was not an accident. It says we will do things properly and have proper consultation with the unions in Wales."
The other main unions in Wales are also divided along the lines of who signed up for the workload deal. The Association of Teachers and Lecturers Cymru and the Secondary Heads Association Cymru are keen to see TLRs introduced as soon as possible, along similar lines to those in England.
The National Association of Head Teachers Cymru, which withdrew from the workload deal after a grassroots rebellion by members, says schools should not be rushed into inappropriate action for the sake of a deadline.
Anna Brychan, director of NAHT Cymru, said: "We want the guidance to be clear about what our members have to do in order and in time to introduce a staffing structure that they and their staff believe will be best for their school."
But while NUT Cymru believes rushing will cause disaffection among teachers who lose out on management allowances and do not receive TLRs, the NASUWT is warning the Welsh that the March 31 deadline will "seriously disadvantage teachers and heads in Wales and cause considerable chaos and confusion".
It is waging a campaign to ensure teachers' pay and conditions remain consistent across the two countries.
The union is also anxious to see the "new professionalism" agenda under development in England - where teachers are rewarded for undertaking professional development and training - being adopted in Wales.
Tim Cox, national executive member for NASUWT Cymru, criticised the Assembly government for endorsing proposals for a chartered status for classroom teachers in Wales which would recognise their expertise but not reward them for it.
He said: "Why should teachers undertake professional development and become much better at their job and not get a reward for that? We are trying to get back on a single track."
New professionalism will also be one of the themes of SHA Cymru's annual conference in Llandrindod Wells in December.