Britain will not have to pay anything to the European Union if it exits without agreeing a deal, a committee of peers has said.
However, it warns of "profound" consequences if the UK leaves the EU without responding to EU budget claims.
EU officials' estimations show the UK owes around €60bn (£52bn) as its share of the budget commitments.
"If an agreement is not reached, all EU law - including provisions concerning ongoing financial contributions and machinery for adjudication - will cease to apply and the UK would be subject to no enforceable obligation to make any financial contribution at all," the House of Lords EU Financial Affairs Committee said in a report.
The committee said the UK will have to weigh the financial and political costs of making payments to the EU to bargain for agreements on things like EU market access.
"If the government wishes to include future market access on favourable terms as part of the discussions on the withdrawal agreement, it is likely to prove impossible to do so without also reaching agreement on the issue of the budget," the report said.
"The political and economic consequences of the UK leaving the EU without responding to claims under the EU budget are likely to be profound."
Britain has two years to agree a deal with the EU after triggering Article 50 - a process that's due to begin this month. After that time, it will leave without one unless all member states agree to extend negotiations.
Prime Minister Theresa May has said the government will consider paying into the EU to participate in "some specific European programmes".
Earlier this week, the House of Lords handed May's government its first defeat on the road to Brexit, amending the Article 50 Bill to include a unilateral guarantee of the rights of EU citizens to remain in the UK.