The introduction of the early years foundation stage (EYFS) will increase the resources needed for primary inspections.
Following the controversial introduction of the new "nappy" curriculum this week, pilots have shown that inspections will require up to double the resources that they have now.
A school which is on the reduced tariff - where the inspection should only take one day rather than the standard two - can now expect either this to rise to two days or the number of inspectors to double. The move comes as Ofsted is attempting to cut costs, with its budget dropping pound;30.6 million compared with last year to pound;199.9m.
According to documents obtained by The TES through the Freedom of Information Act, which evaluated pilots testing the effect of the new curriculum on primary visits, inspectors who took part said trying to make additional judgments during the shorter inspections was "madness".
The two evaluations cover pilots carried out in November 2006 and June 2007. The 2007 report covered 15 state schools. It stated: "One HMI summed up the consensus in this written comment: `It is madness to add a significant burden when we are already pushed to deliver the basic inspection'."
An Ofsted spokeswoman said: "Where necessary, additional resources will be added to the inspection team to allow for the extra judgments being made. This will mean an addition to the allocation of inspector time for reduced-tariff inspections and small schools. The allocation of additional time was explored during trials of EYFS inspections over two years."
The early years foundation stage becomes statutory from Monday for all those dealing with pre-school children. It advocates play-based learning for youngsters, but certain aspects, such as an expectation that children will be able to write simple sentences by the age of five, have been strongly criticised. Judgments will be made on how effective the provision is in meeting the needs of young children and how effectively it is led and managed. Optional self-evaluation forms for the new process are on the watchdog's website.
John Bangs, head of education for the National Union of Teachers, said: "I don't think Ofsted should be inspecting the foundation stage this year. It is going to take time to bed in and there is a review going on of two of the early learning goals. I think it is highly inappropriate for Ofsted to be inspecting something which is in flux."
Mick Brookes, general secretary of the National Association of Head Teachers, said his members were `quite supportive' of the foundation stage but are anxious about assessment and accountability.