Brexit's been the dish of the day in Brussels again, as EU leaders met to debate their future budget.

After the informal summit, European Council President Donald Tusk said he expected the bloc's joint stance on UK future ties to be adopted next month, regardless of whether London gives input. And he fired another warning shot.

"Of course I am glad that the UK government seems to be moving towards a more detailed position. However, if the media reports are correct, I am afraid that the UK position today is based on pure illusion. There can be no cherry picking and no single market a-la-carte," said Tusk.

Brexit will take around 10 billion euros out of the EU budget each year. It comes at a time when there's pressure to increase funding for common policies.

There's a warning that cuts are on the way for big areas of spending, to try and balance the books.

"If we do not reduce the cohesion budget and the agricultural budget, both of which account for 70 percent of the European budget, if we don't do that, we'll have to reduce the other policies by 45 per cent," commented Jean-Claude Juncker, President of the European Commission.

Countries are divided over upping their net contributions. Sweden, Denmark, Austria and the Netherlands have ruled out higher payments. Throw in Brexit as well, and the EU has a cocktail of tough talking and decisions ahead.