Some schools are being threatened with having to return money currently held over from previous years.
NAHT further explored the issue before press in Liverpool in advance of the Annual Conference today.
There is considerable confusion and inconsistency across the country over the amounts and level of monies being held by schools and the reasons behind this.
However Kathryn James, Senior Assistant Secretary, said that over 92% of schools don't have balances beyond the defined threshold.
Of those which do, many schools are holding the money as savings for capital projects which NAHT said was entirely legitimate.
There were many other factors involved and it also transpired that Specialist Schools must carry forward a significant amount of each year's budget to account for the fact that their financial year runs from September to August.
Mick Brookes was careful to point out that "we have no time for any school that is sitting on a major balance without reason".
