The Papua New Guinea Teachers Association says 45,000 teachers will plan a strike if salary discrepancies are not resolved by today.
Its general secretary, Ugwalubu Mowana, says the Teachers Service Commission agreed to implement a negotiated pay-rise at the beginning of the year, but has not followed through.
He says that means 25,000 teachers are not being paid their correct salaries.
"If the state do not make the corrections, and we mean all the teachers in Papua New Guinea on the payroll must be paid correctly according to the award. If that is not done by the end of this month, we will resort to mobilising our membership throughout the country and we will set the date."
Ugwalubu Mowana says the strike will likely be in August or September.
He says the association has been asked by the commission not to strike, but will ignore the request.