Barnet Council is taking urgent action to get its finances under control after revealing its budget gap is expected to soar to £62m by 2025.
At a meeting of the policy and resources committee last night, Labour councillors called for an overhaul of financial reporting after the latest medium-term forecasts turned out to be significantly worse than those made before the local elections on 3 May.
Just three months ago, the council predicted a balanced budget for the current financial year and a gap of just under £6m between spending and resources by 2020.
But the latest forecast shows the budget gap for the coming financial year is expected to be £9.5m, climbing to more than £19m by 2020.
Labour called for the borough's strategic finance team to be brought back in house instead of being outsourced to private service provider Capita.
West Finchley councillor Ross Houston said: "We went through a local election thinking council finances were under control, and, quite clearly, they were not under control - and, quite frankly, I think the public had a right to be informed of that before the election."
Political blogger John Dix, who lives in New Barnet, also expressed incredulity that officers and councillors were not aware how bad the situation had become.
He said: "You sat on this committee six weeks before the election and you had no clue as to the problems? You are right, things do change - but hang on a minute, all that huge difference did not crop up in the six weeks before year-end?
"Voters hold you accountable, but are you getting the information to make those decisions?"
Barnet Council's director of finance Kevin Bartle said officers were getting a "clearer position" on the financial situation in early May - after the local elections had been held.
Mr Dix suggested the council adopt a financial reporting system that is updated on a monthly or weekly basis to give a more accurate picture of its position.
The business planning report states that: "Chief Officers are continuing to work to mitigate this pressure (the £9.5 million funding gap) and recognise their responsibilities to do so under the authority's financial regulations.
"Additional possible actions include control and review of all agency placements and a potential vacancy freeze within the organisation."
In response to Labour's request, Conservative members of the committee said options to bring the strategic finance team in house would be included in the budget update at the next committee, which is due to meet in July.