England's school exam system costs more than £610m a year to run, a report for the examinations watchdog has found.
Reforms have been proposed which would reduce testing
Head teachers' leader John Dunford described this as a "tragic waste" of money - creating a "nightmare scenario" of too much exam red-tape.
He called for more assessment by teachers so that time-consuming and expensive external marking could be reduced.
The exam bill includes £240m for staff time in administering exams in schools.
A further £370m included the cost of exam boards and the Qualifications and Curriculum Authority (QCA) itself.
Consultants PricewaterhouseCoopers said the system, with a "huge amount of superfluous or duplicated information", might be streamlined - which the QCA has said is being done.
Among the examples of red-tape, the report highlights exam boards sending schools information three times a week and producing 1,200 different exam documents.
Dr Dunford, general secretary of the Secondary Heads Association, said that young people in England faced more exams than in other countries - and that the exam system had become too complex and "confused".
He called for a reduction in the number of exams and for teachers to be accredited to assess pupils within schools. This would cut out the bureaucracy attached to external exams, he said.
"It is of vital importance that the government puts more trust in the professionalism of teachers and includes more in-course assessment in final examination grades," said Dr Dunford.
The consultants' original remit had been to produce a model to test various scenarios such as reducing the number of A-level modules.
But a spokesman for the QCA said this was not pursued because it would have cost too much in consultancy fees - so no potential savings are quoted in the report.
Instead it is a snapshot of the main parts of the system as it was in 2003-04.
"Our work has highlighted that the examinations system is a complex area, but that there is scope to make improvements to the processes used," it said.
Exam centres (schools and colleges) might access and update information directly with exam boards, and the information sent to centres could be standardised and better targeted.
Most of those interviewed in schools said the system would be better if either there were a single exam board or if the different boards' administrative procedures were rationalised.
"We noted that one of the main issues for centres/examinations officers is the sheer amount of correspondence they receive," the report said.
One board printed some 1,200 different documents and sent materials to centres one to three times per week.
QCA chief Ken Boston: "Clearly unacceptable" costs for schools
"Simply to receive this, log it, sort it and either respond, file, bin or pass to the relevant staff member is a major time burden."
With bulk mailings, there was a risk of important items being missed.
"Although all the awarding bodies are working on ways of rationalising what they send out to centres, a huge amount of superfluous or duplicated information is still despatched," the report said.
At the QCA the acting head of the National Assessment Agency, David Gee, said it and the exam boards were investing in changing the system and "significant benefits" had been realised.
"The NAA will continue to work with schools, colleges and awarding bodies to ensure that the examination system is fit for the 21st century."
For the report, PricewaterhouseCoopers consulted the QCA, more than 200 schools and colleges, and the three main English exam boards.
The report did not include qualifications typically taken in further education centres, such as BTecs and City and Guilds.
It was commissioned by the QCA chief executive, Ken Boston, who said in September 2003 that the cost of exams to schools was "clearly unacceptable" - though no-one knew what the total cost was.
Commenting on the PWC report into the cost of the English examination system, Shadow Education Secretary Tim Collins criticised the failure and inefficiency of the Qualifications and Curriculum Authority (QCA). He said:
The Conservative education spokesman, Tim Collins, attacked the exam system's "bloated bureaucracy".
"Rather than pointing the way towards higher standards, the QCA has vigorously led the path downhill. In its present form, the QCA is not part of the solution - instead it is the heart of the problem. It needs radical overhauling," said Mr Collins.