Neighbouring Cabonne Council has voted to support Centroc's position following a 17.3 per cent fee increase in the past year, due to an increase in the Volunteer and Statewide Support (VASS) charge, which covers fixed-wing aircraft.

Advice on the increase was provided in December, after councils had already allocated their annual budgets. Cowra Shire Council has refused to cover the increase.

Cabonne mayor Ian Gosper said costs to Cabonne Council had passed $300,000.

"We are taking on the increase this year, but we are supporting Cowra and Centroc," he said.

Cr Gosper said a growing amount went towards administration costs.

"A lot of money goes over the other side of the Blue Mountains ... and is spent at head office in admin and office charges. That's what we're worried about," he said.

"If the money was being spent on trucks, no one would have a problem with that."

Cr Gosper, also the Boomey Rural Fire Brigade's deputy captain, said the council had previously written to the Minister for Emergency Services and the RFS with no success.

"We stipulated that we are not happy with the way the increases come in the middle of the year and the increases keep coming," he said.

"Councils' incomes are set due to rate pegging, which is 2.3 per cent this year. We can't just keep funding increases for everybody when we can't do the same. It's not that we are against the volunteers, the job they do is fantastic."

A report to Cabonne councillors said the RFS needed to be transparent in its spending and council required assurance from the RFS that its money was well spent.

"Every cent required by the RFS comes from another project of council which has funding allocated to it," the report said.

"This could involve roads, libraries or other services, which the community has been advised would be funded that year. Further, such a poor process regarding timeliness can be indicative or poor administrative capability and begs the question in our communities around value for money."

Centroc chair Ken Keith said the VASS charge rose from 20 per cent of the RFS's funding in 1995 to 45 per cent in 2013.

"It should be a CPI increase and if it needs more than that, it should have to justify it, but do it before councils set their rates," he said.

Centroc's board will decide on its next move at its May meeting.

The Rural Fire Service late last month said it had taken into account Cowra Council's concerns over the budget rises.

"The 2014 NSW Rural Fire Service budget proposed an additional firefighting vehicle worth $300,000 be given to volunteer brigades in the Cowra area," a spokesperson for the RFS said in a statement.

"Taking into consideration the Cowra Council's concern over the increased budget, the vehicle has now been allocated to another area to allow the Council's contribution to be consistent with the 2013 budget."