Council leaders in Walsall warn extra services could be cut and more jobs lost as they have to cut another £20m over the next five years.
It had been thought the council would need to save £80m, however, the figures have now been revised to £100m.
Two years ago the council announced 430 redundancies. Leaders have warned there could be more in the future.
They said no decisions had been made about where the cuts would fall yet but expected to have proposals by October.
The council, which no party has overall control of, said it had already made £32m of cuts from the past two years.
Council leader, Conservative Mike Bird, said the fall in council funds was partially because the authority had been prevented from increasing council tax over recent years, which meant that with inflation, they had less money overall.
He added that the borough's increasing ageing population meant there was more pressure on some of its services, meaning they were having to provide "more for less".
'Level with everyone'
Mr Bird said: "Over the last three years we've taken over £40m out of the budget but the low-hanging fruit has gone and we've either got to prune the tree or chop it down altogether.
"While we all accept the country is in a terrible state, local government in my view is having to deal with more than its fair share of problems, cuts and everything else."
He added it was "important that we're level with everyone".
He added that officials were looking at ways some of the council's services could be shared with other public bodies, for example with IT services.
The council said staff had been told the authority was facing the extra cuts in a message from the chief executive.
Chris Towe, the councillor in charge of finance, said it was "very difficult times".
He added: "But we won't be deflected from helping business create jobs and help Walsall people to find work.
"There's a range of things we're focussing on because they are important to Walsall people."
Mr Towe added: "We know the size of the problem and we'll endeavour to deal with it as best we can to minimise the impact on staff and residents."
The authority has now started a consultation with local residents to ask for their views on how more money can be saved and which services could potentially be cut.
Some proposals are expected to be drawn up by October, after which time residents will be asked for their views again.
The final budget for 2014-15 is expected to be set in February.
In a statement, a spokesman from the Department for Communities and Local Government said it was "disingenuous" to suggest there would be "further budget reductions since the total amounts allocated to local authorities have not changed since the spending round".
He added: "To help tackle the deficit left by the last administration, in the recent spending round, the coalition government set out a saving of 2.3% for 2015-16 in overall local government spending, including funding from central government, business rates and council tax income.
"This change is balanced with a progressive package of measures which create a real opportunity to transform local services and help deliver better outcomes for less."