The former UKIP leader lashed out over Twitter after the EU agreed talks could move on to the second phase – but not without a long wait.
Leaders say additional guidelines need to be adopted at a future summit next March before trade is discussed, despite Mrs May having faced a race against time to agree on withdrawal terms for this month’s summit.
And he said it was “no wonder” the Prime Minister had received such a rapturous reception when she had dinner with EU leaders yesterday.
Mr Farage wrote: “If the trade talks don’t start until March then why did Theresa May leave Downing Street so early last Friday?
“We’ve been taken for mugs, no wonder the EU leaders applauded her last night.”
Today’s Brexit agreement was made in a meeting of the leaders of the 27 remaining EU states lasting less than half an hour in Brussels in the Prime Minister’s absence.
Guidelines agreed at the European Council summit revealed that the EU expects Britain to remain under the jurisdiction of the European Court of Justice and permit freedom of movement during a transition period expected to last two years after the official date of Brexit in March 2019.
European Council President Donald Tusk announced the decision on Twitter, saying: “EU leaders agree to move on to the second phase of Brexit talks. Congratulations PM @theresa_may.”
And Mrs May responded by thanking Mr Tusk and European Commission president Jean-Claude Juncker, adding: “Today is an important step on the road to delivering a smooth and orderly Brexit and forging our deep and special future partnership.”
Mrs May left the two-day summit early after winning applause from the other leaders as she assured them on Thursday evening of her determination to see Brexit through despite this week’s defeat in the House of Commons.
The EU position set out in the guidelines makes clear that any transition period agreed by Brussels “must be in the interest of the Union, clearly defined and precisely limited in time”.
Under the proposals, the UK will be required to follow the EU rulebook in its entirety – including laws adopted during the transition period – while playing no part in the decision-making processes of the European institutions.
And the guidelines make clear that Britain will be expected to observe the single market’s “four freedoms” of movement of goods, services, people and capital during the period, expected to begin on March 29 2019.
Labour MP Chuka Umunna, on behalf of the Open Britain campaign for close ties with the EU, said ministers are now being confronted with the “sheer complexity and monumental costs” of Brexit, and are ill-prepared and have “insufficient time”.
He said: “Contrary to the claims of Brexiters who said that trade talks would begin speedily, we now won’t be able to discuss the future relationship until March at the absolute earliest.
“And the Cabinet has still yet to even discuss – let alone agree on – what form of relationship it wants the UK and the EU to have.
“The clock is ticking, and we are far away from anything resembling a deal.
“Brexit is intractable and complicated, far more so than people were told at the time of the referendum.
“Voters have the right to keep an open mind about whether this is really the best future for our country.”