Kingston upon Thames LBC is expected to overspend by £4m this year after finding a third of planned savings may not be delivered on time.
The council's latest finance and contracts committee meeting heard evidence that the borough could miss £8m of the £22m savings it has planned for 2018/19.
Kingston blamed a shortfall in commercial property income, delays to savings on commissioning and contract management, staff restructuring taking longer than planned, and the soaring costs of asylum seeking children and special educational needs services.
Lib Dem council leader, Cllr Liz Green, took over from the Conservatives after this year's elections.