Local authorities in England are failing to refer poor teachers to their disciplinary body, a report suggests.
Less than half of councils have reported a teacher to England's General Teaching Council, which has the power to strike off poor teachers, it said.
The joint GTCE and government report said some employers were uncertain about their responsibilities for referring cases of incompetence.
The GTCE is writing to local councils to remind them of their duties.
It also plans to review the advice and guidance it offers to schools and local councils to ensue there is an improved understanding of regulation issues.
The research found inconsistencies in the way local councils approached referrals.
Some employers were anxious about referring cases because they feared a report would automatically lead to a teacher's removal.
Others feared the GTCE would be too lenient, it said.
But the body said neither worry was well-founded because its committees considered each case on its merit, it added.
Chief executive Keith Bartley said: "This report suggests that there is considerable activity on the part of employers locally to ensure that children and young people are taught by high quality teachers and it reflects upon the level of commitment and training that teachers demonstrate.
"However, the report also reveals inconsistency of understanding and practice with regard to referrals made by local authorities to the professional regulatory body."
He added that the research provided some clear insights into reasons for these inconsistencies.
Schools minister Vernon Coaker said there was a legal duty on employers to refer cases of teachers who had been dismissed or had resigned on the grounds of incompetence.
He added: "Employers need to ensure that they take seriously their statutory responsibilities in this area.
"We expect the GTCE to fully exercise its regulatory role in respect of those teachers who fall below the high standards of practice expected of them.
"What this report identifies is the need to continue to communicate the legal duty on employers in the case of referral and so we welcome the GTCE's action plan to do this."
All qualified teachers have to register with the GTCE, which has a duty to improve standards of teaching and the quality of learning.
Since the GTCE began hearing cases in 2001 it has considered 664 professional conduct cases and 75 competence cases.
But only 13 prohibition orders, 1 suspension orders and 11 conditional suspension orders have been issued.
If a teacher is found to be seriously incompetent, the GTCE can impose a range of sanctions from reprimand, through to a conditional registration order requiring remedial action.