Dr Jonathan Ford, the former managing director of the National Assessment Agency, resigned last November after a Qualifications and Curriculum Authority inquiry found that last year's key stage 3 English tests, which were his responsibility, were "plagued with a myriad of errors".
Hundreds of schools complained after some pupils were awarded grades up to five levels lower than expected.
Last year's national results were published three months late because of the problems, andmany staff were forced to work into the summer holidays to check pupils' scripts for marking errors.
When the QCA's annual accounts were published in July, details of Dr Ford's salary, benefits and whether there had been a pay-out were omitted, at his request.
The TES challenged the omission under the Freedom of Information Act. The regulator originally rejected this request outright. Now, after an appeal, it has agreed to release Dr Ford's basic salary and benefits which came to Pounds 116,394.96 in 2004-5. But the QCA appeals board refused to give any details of Dr Ford's pay-off.
The board said: "The terms on which Dr Ford's employment ended are covered by an explicit and contractual duty of confidence. Given the express confidentiality terms agreed, Dr Ford has no reasonable expectation of any information about those terms being made public."
Thus, the QCA said, releasing the information would be unfair and in breach of data protection principles. This outweighed public interest considerations.
Maurice Frankel, director of the Campaign for Freedom of Information, said:
"It is in the public interest to know how much public money is being spent on pay-offs to senior staff."
The TES is to challenge the QCA's decision with the Government's information commissioner.