Online recruitment company Eteach lost nearly pound;1 million after a year in which it was criticised by teachers for failing to find them work.
The firm has published late annual accounts which show that, up to July last year, it made a loss of pound;970,171, taking its total losses since its launch five years ago to more than pound;4m.
Eteach has testimonials from many school staff who have been pleased with its service.
But it has been criticised by several teachers who say it has not found them work, that they have not been fully paid, or that they have become frustrated after waiting months to be registered with the company.
Eteach's performance last year was affected by its decision to buy Go Temping, one of its main competitors, which runs the Go Teaching website.
Paul Howells, chief executive of Eteach, admitted that the company had difficulty coping with the extra teachers who joined its books after it bought Go Temping.
"We were surprised at the numbers we encountered and we struggled," he said. "We did get an awful lot of flak for that but we have held our hands up about it."
The former supply teacher, now an Ascot-based multi-millionaire, stressed that payment failures were a matter for local authorities as they handled the teachers' pay-rolls.
He has apologised to those who had been affected by problems registering, saying the company's system has since been improved.
Mr Howells said difficulties finding jobs for teachers last summer had been related to changes in schools' workforces, as more opted to use classroom assistants rather than trained teachers.
But he said that demand had picked up this year and that he was optimistic for the year ahead.
Eteach appears to have overestimated the worth of Go Temping, as it paid Pounds 1.3m for the company in May last year but valued it at pound;750,000 two months later.
Eteach and Go Teaching are due to be merged into a single business by the end of the year.