But board of trustees chairman Steve Fielding said the school was unlikely to appeal the new ranking because of the sheer workload of trying to dispute it.
While other North Otago schools have risen by one point, stayed the same or dropped by up to two points, Duntroon has risen four points from five to nine.
The higher the decile rating, the less money from the Ministry of Education, which has a focus on improving low-decile schools.
Mr Fielding said he suspected there was an attempt to move more money to the North Island, particularly its northerly parts.
The change would mean the school would lose about $6000 a year from its budget which would have a major impact on a school with a roll of only 70 pupils.
''We'll have to find something else to replace it - more fundraising,'' he said.
Mr Fielding found it difficult to identify what had produced such an effect on the school's decile rating, but the school would probably have to just accept it and adjust with belt-tightening.
Asked if the increasing number of dairy conversions in the area from new irrigation, bringing more employment, along with previous high dairy payouts could have had an effect, Mr Fielding was unsure.
The decile system is used to allocate funding to state and state-integrated schools to help overcome the barriers to learning faced by pupils from lower socio-economic communities.
Addresses of a school's pupils are used to determine which areas it is drawing pupils from, then five factors - household income, occupation skill levels, household crowding, parents' educational qualifications and parents on benefits - in those areas are assessed.
