Cuts at Somerset County Council have been called "hasty and damaging" by the opposition leader.
About 1,500 staff are to lose their jobs and staff that remain could face pay cuts. Adult social care, libraries and road maintenance will be hit.
The cuts have led one cabinet member to resign. The Lib Dem opposition and unions say the decisions are premature.
The Conservative-controlled authority said it faced a 25% funding cut over the next four years.
The council has a £76m budget deficit and a debt of £400m.
Opposition leader Jill Shortland said: "The cuts are all too hasty and there needs to be a bit more thought going into it because I think some services are being slashed when maybe they don't need to be."
She said the council was taking decisions before it knew its final allocation of money from central government.
Nigel Behan from Unison said the authority was going "much faster than even the government".
So far this year nearly 200 people have taken voluntary redundancy. A further 500 staff are to leave by April however their redundancy pay will be worse than those that have already gone.
The remaining 800 posts are to close over the next three years.
Ms Shortland said: "Of course there are going to need to be some job cuts - everybody accepts that - but before you spend more money on making people redundant, before you make any hasty decisions about services, let's have a look at this in a properly planned way."
The authority's chief executive Sheila Wheeler said the authority was not "running around like headless chickens".
"It will be horrendously difficult," she said.
"My email box is full of heart-rending emails about people who are very anxious about how they continue to provide a decent quality of lives for their families and their children; meeting their mortgage commitments and their ongoing daily requirements."
She said the council could not wait a month for the information on funding to filter down from central government as it was their "duty to balance the books".