The 27 EU leaders will try to break the deadlock over the Union’s budget for 2014-20 at yet another summit in January or February.
Although there is no formal deadline, the closer it gets to 2014, the greater the risk that its spending programmes would be disrupted.
The betting in Brussels is that there will be agreement early next year. Another failure would be hugely embarrassing. If there is no deal, the EU would switch to annual budgets, which would rise by at least two per cent each year for inflation.
They would be approved by qualified majority voting, depriving Mr Cameron of his veto, and so could result in a bigger EU bill for British taxpayers.
That might be difficult to get through the House of Commons, which voted for a cut in EU spending last month, landing the Prime Minister with a big headache. So he will have an incentive to sign up early next year.