BORIS Johnson has insisted that the only remaining Brexit options are "no deal or new deal."
If the UK does leave without a deal it would back into the World Trade Organisation (WTO) rules. But what does this mean and how would it work?
What's the latest on Brexit?
The UK has hinted it might "clarify" its new Brexit offer after the EU called for "fundamental changes".
The EU snubbed the UK's proposed alternative to the Irish backstop, saying it could not be the "basis" for a legally-binding treaty.
The UK has said it would work on the details before then but there was "no path" to a deal without alternative arrangements in Northern Ireland.
Boris Johnson has insisted the only options are a "new deal or no deal".
He also posted a message on social media saying there would be "no delay" to the UK's exit beyond the Halloween - despite governmental insistence the PM would have to request a further extension if no deal was agreed by October 19.
What are the WTO rules?
The WTO is where countries negotiate the rules of international trade.
If they do not make any free trade agreements they will trade under WTO rules.
Every member of the WTO has a list of tariffs and quotas that they apply to other countries – which is known as WTO schedules.
Does the UK already trade with other countries on WTO rules?
The UK does trade with other countries as part of the EU.
In the event of a No Deal Brexit the UK would have to forge trade deals that the EU already has with other countries.
The UK has not signed any free trade deals yet but a deal with Switzerland is close and a more limited deal with Australia and New Zealand has been agreed.
What is a No Deal Brexit?
A No Deal departure from the European Union means leaving without formal arrangements for the future relationship or any transition period.
Currently Britain's trade, customs and immigration rules are tied up with the single market and a host of EU regulatory bodies.
The UK will automatically head towards a No Deal if no agreement is made with the EU on a withdrawal deal by October 31, 2019.
On August 18, it was reported that Mr Johnson will meet the leaders of Germany and France with a stark message: MPs won’t stop Brexit.
The PM will use a two-day trip to the continent to insist the referendum result will not be delayed again beyond October 31.
He will say that we are leaving with or without a deal.
What happens in a No Deal Brexit?
The UK will have to agree to a new list of tariffs and quotas once it is no longer part of the EU.
Many who support leaving without a deal reference the Trade Facilitation Agreement (TFA), which obliges to treat the UK fairly.
However, the TFA is aimed and less developed countries and even though it cannot discriminate against the UK, it cannot expect to be treated the same.
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The UK will immediately have to leave EU institutions including the European Court of Justice and Europol.
Businesses would lose their passporting rights, which allow them to sell their services across the EU without having to obtain licences in each individual country.
The UK will no longer contribute to the EU budget - currently about £9bn a year.