An exam board has raised its pay rates for markers by about 25% in some subjects to try to tackle a shortage.
AQA - largest of the big three English exam boards - says there are problems recruiting markers in subject areas such as English and psychology.
Its chief executive, Mike Cresswell, said: "Last summer our pay rates would have averaged about £12 an hour.
"The increases aren't across the board but the rates have gone up by quite a chunk to about £15 an hour."
The three boards joined forces for the first time earlier this year to mount an examiner recruitment campaign, which has brought forward an extra 4,000 would-be markers.
The target was to recruit 3,000 more, on top of the usual 60,000 or so.
The National Assessment Agency which now manages exams - part of the QCA watchdog - has said it is making available an extra £15m to pay them this year, about 15% of the overall exam modernisation budget.
It said this would result in the majority of examiners receiving a rise of about 5%, although some would receive more.
The recruitment literature says the level of remuneration "depends on two things - the number of papers or amount of coursework you agree to mark or moderate and the level and length of the work you are marking".
It adds: "Generally, the higher the level and longer the paper, the more complex and time-consuming it will be to mark."
Essay-based subjects involve more time than "right or wrong" answers.
The biggest risk that the system is running is shortages of examiners in some key subjects," Mr Cresswell said in an interview with The Independent newspaper.
"It is not across the board at all but it remains a problem. There is a lot of work going to overcome it. It hasn't actually stopped candidates getting their results on time over the last few years."
More than 20 million exam scripts will be marked this summer - with AQA alone handling some 13 million: 10 million GCSE papers and three million A and AS-level scripts.
There is widespread concern that the system has become overloaded.
Mike Tomlinson, heading the government-commissioned review of 14 to 19 education in England, regards reducing the "assessment burden" as one of his priorities, particularly in AS and A2 exams - the two parts of the A-level.
Exam boards are experimenting with electronic marking to reduce the bureaucracy involved.