With members across England and Wales, the Teachers' Pension Scheme is one of the largest retirement schemes in the UK.
Although day-to-day operations are outsourced to Capita, the DfE has overall responsibility for the scheme.
But in a letter seen by Money Box the NAHT said it had "serious concerns" about how it was being run, including significant delays for members being paid their pensions.
The letter also cited excessive waiting times for members trying to get through on the phone, poor communication from pension scheme staff, and unanswered and unresolved queries and complaints.
Describing its members as "deeply dissatisfied", the union's assistant general secretary James Bowen said it was clear the Teachers' Pension Scheme was failing teachers and school leaders.
"It's just frankly not good enough," he said, adding that the department and the pension scheme needed to "get to grips" with the problems and accelerate resolving some of the queries.
"I think we need to see some strong leadership within the Department for Education and within the Teachers' Pension Scheme," he said.
"Probably the only other solution is to put some more capacity into that team so it can cope with the demand that appears, at the moment, to be overwhelming them."
[SRC] https://www.bbc.co.uk/news/articles/cm2zvj2ex70o
