Organising exams is a complex job that used to be done by senior teachers - but now it pays as little as pound;15,000 a year.
Schools are hiring staff to organise their GCSE and A-level exam entries on a third of the wages they were previously paying teachers to do the job, The TES has been told.
Andrew Harland, chief executive of the Examination Officers' Association, said his members typically earn pound;17,000 a year for a job previously carried out by senior staff, who with their other duties earned more than Pounds 40,000.
The changes have come as a result of the workforce agreement, which since 2003 has led to thousands of exams officer roles transferring from teachers to administrative staff.
But in an interview with The TES, Mr Harland said that the exam officer role had become much more important to schools since the introduction of the Curriculum 2000 reforms, which led to a surge in exam entries.
Officers have varied responsibilities ranging from processing entries and timetabling exams to checking that coursework deadlines have been hit and even training exam invigilators.
Some officers are dealing with pound;100,000-plus exams budgets, said Mr Harland, and often have to work through their lunchbreaks and after school.
Mr Harland said the low wages meant many would leave schools after only a few years. He said: "This job is not about pushing paper and pressing buttons. Exams officers have to have financial management skills, to be able to build up good relationships with teachers and need good computing abilities. The salary should reflect this."
Belinda Smith, 44, said she is leaving a school in Chesterfield, Derbyshire, without a job to go to this month because of her frustration that the school turned down her request for extra administrative support.
Mrs Smith, who is not a teacher, is paid pound;15,000 a year for a 44-week, 37-hour-a-week job.
She said: "The exams system is so complicated. Even senior management rely on me to know the rules and regulations of exams, but I'm underpaid for the amount of responsibility I have."
Mr Harland said the workforce agreement, though positive in part, had been a "problem" for many staff.
Some qualified teachers who had been working part-time as exams officers had not wanted to go back into the classroom full-time, and are giving up teaching altogether.
Mr Harland was speaking as his association was about to be relaunched this week as a charity with an elected group of trustees.
It was founded four years ago after Mr Harland, a former geography teacher who became exams officer at St Joseph's convent school in Reading, and two other officers became frustrated at the lack of a support network.
Some 2,500 of approximately 6,000 exams officers in Britain are members of the EOA.
It is funded by the National Assessment Agency, an arm of the Qualifications and Curriculum Authority, which also employs Mr Harland.
Despite this, he said the association felt free to speak out against Government policy.