Theresa May faces being publicly criticised by the EU if her letter triggering article 50 fails to refer to Britain’s obligation to settle its divorce bill and make an “orderly withdrawal” from the bloc.

A failure of the UK to announce its intention to act in good faith over the terms of its withdrawal, including a multibillion-pound financial settlement, is likely to receive a swift and condemnatory response, senior EU sources have suggested.

It is understood the EU’s Brexit negotiating team would expect the European council, the body that represents member states, to publicly point to the UK’s failure to offer clarity on its intentions.

It would mark the worst possible start to the negotiations, which are expected to be formally triggered in the last week of March. There are fears on both sides that intransigence and escalation of rhetoric over the withdrawal bill could lead to an early end to talks, and the UK crashing out of the EU without any sort of deal.

Senior figures in the European commission have noted May’s reluctance to comment publicly on the financial liabilities the UK will need to meet. The prime minister has preferred to talk about her hopes for a comprehensive free trade agreement.

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However it is estimated that the UK will need to pay about £57bn, to cover the pensions costs of EU officials, budget commitments it has already made and contingent liabilities, which are costs that may arise in the future but cannot yet be calculated.

A source said that while the commission was open to compromise on the sum the UK would have to pay and wished to avoid any early clash on the issue, the member states were seeking the maximum recompense. “They are the hawks on this,” one senior EU source said.

The UK currently pays about 12% of the EU’s budget, and its withdrawal will leave a huge hole in the bloc’s finances.

May will be expected to both acknowledge the UK’s financial obligations in her letter of notification and then, as talks open, agree in principle on the methodology that will be used as the UK leaves to calculate the bill.

A senior EU source said, however, that the commission would not land May with a large bill in the early stages of the talks, in recognition of both the hostile reaction that would be likely in the House of Commons and the difficulty in calculating the appropriate sum until the UK has actually left the union.

The trade secretary, Liam Fox, has described suggestions that the UK needs to pay a large bill as “absurd”. The MP and former cabinet minister John Redwood MP has said there is no legal basis to the demands. “I don’t see why we should have to pay,” Redwood said last month.

The commission had expected May to make the notification on 14 March, but now believes she will write to Donald Tusk, the president of the European council, on 27 March.

It has been claimed there is disagreement in the heart of the UK government about how much detail May’s letter should go into in terms of headings for discussion and schedules of topics, and that this is partly to blame for the delay in notification.



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Although member states believe a letter of notification at the end of March will condemn the opening of negotiations to be delayed until June, the commission hopes to speed things along and start negotiations in the middle of May.

Alongside agreement about the methodology used to calculate the UK’s liabilities, there will attempts to find common ground on the rights of EU nationals in the UK, and UK nationals in the EU.

Only then, a senior source said, would it be possible for the EU and the UK to scope out how a free trade deal might work. The commission will not negotiate in earnest on that until the UK has formally withdrawn, making a transitional agreement essential for key parts of the British economy, including the financial services sector, which relies on passporting rights to work across the continent.

However, it is understood that the commission’s Brexit negotiating team, headed by Michel Barnier, is currently spending much of its time preparing for the event of the UK leaving the EU without a deal.