The cost of leaving the European Union could leave Britain with a "divorce bill" of up to €20 billion (£18 billion).
That's according to the Financial Times, which also claims that responsibility for more than €300 billion (£270 billion) of shared payment liabilities will have to be settled in Brexit negotiations once Article 50 is triggered.
The FT's €20 billion "upper estimate" would include the UK's share of continuing multi-year liabilities, including an approximated €241 billion (£217 billion) of unpaid budget appropriations, pension liabilities estimated to number around €63.8 billion (£57.5 billion), and other commitments amounting to roughly €32 billion (£29 billion).
The FT said the analysis represented the first attempt to quantify the Brexit bill, but some officials in Brussels have warned the final figure could be even higher.
The Government refused to comment on the report.
A spokesman said: "As the Prime Minister has said, we will invoke Article 50 no later than the end of March next year.
"We are not going to provide a running commentary on leaving the EU."