Nearly £400,000 has been spent in a bid to avoid public confusion over a new system for the way GCSEs are graded in England.
From this summer, GCSE results will begin switching from letter grades such as A* or G to a numerical system, with 9 the highest grade.
The government wants to "promote understanding" of the new grades.
The exams watchdog Ofqual says explaining the new system to the public is "essential".
In a parliamentary written answer, ministers revealed that more than £380,000 would be spent on information for students, parents and employers about the new 9 to 1 grades.
This summer will see pupils getting their English and maths results in numerical grades, with other subjects to convert over the next few years.
It will end letter grades for GCSEs, used since the 1980s.
This switch will apply only in England, with GCSEs awarded in Wales and Northern Ireland to retain their letter grades.
The question about spending on the new format was asked by Labour's former shadow education secretary, Lucy Powell.
She warned that the changes could cause "chaos and confusion" and labelled the switch to number grades as an "expensive vanity project".
"With just weeks to go before GCSE results are announced, parents, business and pupils remain unclear on what these new GCSE grades mean in practice," she said.
The new grading system is intended to send a signal that these are a different type of GCSE, moving away from coursework and modules to results based on final exams.
But there have been warnings over confusion in what will constitute a pass in the new grading arrangements.
There are going to be two different pass grades - a grade 4 as a "standard" pass and a grade 5 as a "strong" pass.
Universities which can require a pass at maths and English GCSE as a requirement have varied in which "pass" they are accepting.
Head teachers' leader Malcolm Trobe said pupils had a good grasp of the new grading system but he thought parents would be less well informed and that employers would be even less aware of the changes.
Professor Jo-Anne Baird, director of the department of education, St Anne's College, University of Oxford, said the cost of the information campaign had been a "drop in the ocean" in the wider costs of exam changes.
"The costs of the examination reforms have been colossal and it is questionable whether it has been worthwhile," said Prof Baird.
"Our examination system is in a perpetual state of reform, caused by different ministers wanting to put their stamp on the system."
A spokesman for Ofqual said 600,000 students would have taken the new GCSEs this summer and it was "essential to communicate these changes to a wide audience, including students, teachers, parents and employers".
"The money has been spent on the development of original films, which have been viewed around 10 million times, as well as printed materials and social media advertising.
"Independent research conducted on our behalf indicates that understanding of the new grades and the reforms has increased as a result of the work we have done."