Up to 650 jobs are to be axed at City of York Council as the authority aims to save £50m over the next six years.
The council had initially said 200 posts would go but the number has been revised after assessing the impact of the government's Spending Review.
Andrew Waller, Liberal Democrat council leader, said management they were working with unions to reduce the need for compulsory redundancies.
The council currently employs 5,500 staff.
Mr Waller said frontline services would remain a priority.
He said: "We are carrying a lot of empty posts, we have had a recruitment freeze for a while now, and in any usual year between 400 and 500 people leave the council to retire or go to other jobs... therefore we're trying to manage this in a way that reduces the need for compulsory redundancies."
He added: "We've been talking with our partners in the health service and police over a number of years about sharing services, sharing back office and accommodation and those are all ways in which we can reduce costs."
The council leader also said it had already reduced the number of directors, assistant directors and senior managers.