Councils in England overspent £816m on children's services in 2017/18, according to official figures.
Analysis of the figures by the County Councils' Network (CCN) found counties overspent the most, spending 10% more than they had budgeted for on children's services.
CCN said the overspend was caused by escalating demand for services, with the number of children under a protection plan increasing by 35% in the past six years.
Chairman of CCN, Cllr Paul Carter, said: ‘Today's figures show the stark reality facing counties, which have had little choice but to overspend millions on vital care services to protect the vulnerable and elderly.'
CCN said county authorities needed to deliver £1.39bn of savings by 2020 to avoid overspends in areas such as children's services and adult social care.
