The document, seen by The TES, was sent out to DfES staff late last month.
It gives details of the 1,460 posts due to be cut by 2008 and the "different kind of department" its leaders want to see emerge as a result.
The department would, said the memo, be "smaller and more strategic, focused on fewer priorities and policies, energising people in the system to lead and deliver improvements, with the department doing less direct delivery".
Civil service unions believe this means that there will be a bigger role for local authorities and quangos such as the Learning and Skills Council.
Tony Cowley, the DfES president of the Public and Commercial Services Union, said: "Will the Secretary of State be prepared to have different standards of provision in different parts of England and Wales? Because that is what will happen."
The document reveals that the number of posts expected to go by 2006 in the first phase of cuts has risen to 850, from the 700-800 which were originally expected.
Some 400-500 job cuts will come from about 2,500 staff employed in London, 230-270 from 1,200 based in Sheffield, 60-90 from 600 in Darlington, and 60-90 from 500 in Runcorn.
More than 85 per cent of the posts expected to go are at relatively junior grades.
Mr Conway said staff were resentful because it appeared that no posts would be lost from the top four civil-service grades.
All directorates would take around a 30 per cent cut. But parts of the children's and young people's directorate - which only recently expanded, taking in Department of Health staff to deal with the Children Bill reforms - would see cuts as early as next month, said Mr Conway.
The memo says that the DfES could end up taking on more staff in some areas if pooling across the wider education sector is judged to offer value for money.
But it also says that outsourcing remains an option. The DfES will continue to use outside consultants and may need to recruit more people with specialist skills over the next five years.
A DfES spokeswoman said the department was being reorganised as part of a government-wide drive to deliver better-qualitypublic services.
She added that at a time when the DfES is under pressure to keep costs down and direct more money to front-line services, the changes would make the DfES more strategic and professional.
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