Significant cuts in services are "inevitable" at Bath and North East Somerset Council after a lower than expected government grant settlement.
In a statement the council said more cuts to jobs than the 300 already announced may need to be made.
The money given to the council by government will go down from £43.5m to £36.7m in 2011/12 and a further cut of £3.6m will be made in 2011/12.
Councillor Malcolm Hanney said the cuts were worse than expected.
The member in charge of resources said: "We currently collect £50m for government and only get back £33m."
He added that the level of cuts being made to the authority's budget were "of an unprecedented nature".
The council said budgets for the next two years would be hit "especially hard" and the cuts were 4.7% higher than expected.
In North Somerset, the council said its settlement was £5m worse than expected for 2011/12.
The leader of the council Nigel Ashton said he would demand a meeting with Communities Secretary Eric Pickles.
"This is a devastating blow for us. Everyone across the council has been working incredibly hard to identify savings for the coming year and the years ahead. But it's simply not enough," he said.