In a report to the council’s cabinet, external, the authority said it was facing its “most challenging budget” and would need to make a number of “very difficult decisions” in the coming financial years.
It said it had “reached the point where it is unable to find the level of savings required to balance the budget on a recurring and sustainable basis”.
It said it is facing a £89.3m shortfall over its four-year medium term financial plan.
This could be reduced to £48.2m if savings identified – but not made public – were approved during its budget setting process in March.
It said the reasons for overspending in the current year were increasing demand and inflation pressures in adult social care, children’s social care, special educational needs and homelessness.
The council also said it had the 37th lowest, out of 99, Band D council tax of unitary authorities and metropolitan boroughs in the country.
It said it had always made a decision to keep council tax as low as possible, but this was “no longer a sustainable policy”.
This year six councils were given permission by the government to increase their council tax above 5%.
