Red-faced civil servants last year discovered that funds for flagship projects - including the Children's Plan consultation and the Byron review - had been agreed without legal permission.
The error encompassed 29 Department for Children, Schools and Families contracts totalling Pounds 35 million, including Pounds 7.6m on Together for Children, a Serco-run project to help councils set up children's centres, and Pounds 455,000 on training materials to support child death review procedures.
Department officials alerted the Treasury last March over concerns that the Education Act 2002, which allows the Secretary of State to "give financial assistance for purposes related to education or childcare", did not authorise Ed Balls to enter into contracts for services such as carrying out a survey of young people's views on smacking or publishing various magazines published by the department.
Emails between the Treasury and the DCSF, obtained by The TES, reveal that "the department has entered into a number of contracts for which it now understands that the authorising legislation for incurring such expenditure is in doubt".
The mix-up meant that the department had to go to the Treasury to ask for retrospective approval for the money to be spent, just two weeks before the end of the financial year - permission it then received.
There is nothing unlawful about the expenditure, but the department has confirmed that it is a "relatively infrequent occurrence".