Sadtu in KwaZulu-Natal is locked in a war of words with the provincial education department over the docking of salaries of teachers who took part in June's public servants' strike.
The department informed all teacher unions on Monday that it would go ahead and deduct money from their salaries for the June strike.
Some 45000 teachers have submitted affidavits saying they did not take part in the strike.
Ntombi Ntshangase, Sadtu's provincial chairman, said the union was perturbed about the deductions because its members had paid back for the 21-day strike by conducting recovery classes between July 9 and September 29.
"We tried to persuade the department not to deduct any money, but were told that the national Treasury wanted to implement the no-work, no-pay policy before the end of the financial year," she said.
"Teachers have told us money was deducted, but that they were not paid for their recovery-plan duties, which should have come through in August," Ntshangase said.
She said Sadtu would continue demanding that all teachers who were on leave during the strike be reimbursed.
"We represent teachers who were on leave and not those who have claimed, through sworn statements, that they were intimidated. We also represent teachers who took part in the recovery plan, yet had money deducted," said Ntshangase.
Christi Naude, education spokesman, said the no-work, no-pay policy is an international norm.
"We did not budget for recovery-plan payments, but knew we could use the money from the deductions. We consulted with all the unions. Some of them accepted the no-work, no-pay rule, but pleaded that we make double deductions in November because they will receive double payments for the recovery plan," Naude said.