The independent schools sector has delivered its grim view of the school funding model, saying it will never be fully implemented.

The national school funding model is haphazard, incoherent and unlikely to ever be fully realised, independent schools say.

The Independent Schools Council of Australia delivered its grim view of Labor’s national school funding plan at a Senate committee hearing on Thursday, labelling it an unachievable reform.

The inquiry is examining how new money is being rolled out to the states and territories and how close funding arrangements are to the recommendations of David Gonski’s report.

That report formed the basis of the previous Labor government’s national plan for school improvement, of which the coalition has not fully adopted with its plans for WA, NT and Queensland.

ICSA argues that far from being national, there are 27 different funding models in operation with each jurisdiction striking a different deal with the commonwealth.

National reform was always unachievable because of the constitutional state responsibility over education.

Moreover, the Abbott government has only committed to the initial four years of the original plan, rendering it unlikely to ever be fully implemented.

“Regrettably, independent schools are left with the consequences of the inability of nine governments over the past three years to devise a better funding model,” ICSA executive director Bill Daniels told the hearing.

“(In) reality we have a more complex situation than existed before. This is most unsatisfactory.”

Mr Daniels’s comments came after the federal education department backed the government’s claim that the amount of funding given to schools would not necessarily lead to better student results.

Associate secretary Tony Cook said some countries were performing better than Australia academically, despite spending less public money on their schools.

“When you get to the level of how much money is making a difference, that’s a very difficult question to answer,” he said.

The Australian Education Union wants the full, six-year roll-out as imagined by Labor because the majority of funding is unlocked in the last two years.

If that doesn’t happen, it will fail a generation of kids who won’t get the same funding as their predecessors, it says.