The arrangement, originally signed in 2009, came in connection with the long-running dispute between the United States and the EU over Europe's ban on beef from cattle treated with certain growth-promoting hormones.
The EU will maintain until 2 August 2015 its duty-free tariff rate quota for non-treated beef, covering some 45,000 tonnes per year, the Department of Agriculture and US Trade Representative's office said in a joint announcement.
In the year since the current phase of the arrangement started, American beef shipments under the quota were valued at about €151 million, up 300% from the year before the agreement came into force.
"Before the memorandum of understanding was signed, the EU's beef market had been largely closed for far too long," US Trade Representative Michael Froman said.
In February, the EU dropped its ban on other US meat imports in a gesture aimed at starting talks on a free-trade pact that would encompass about half the world's economic output.
Brussels and Washington want to deepen a relationship that accounts for a third of global trade, and ending the EU import ban on live pigs and beef washed in lactic acid is meant to show the Europeans are serious about a deal.
Europe has long objected to US hygiene and husbandry methods in meat production.
The lifting of the ban took effect on 25 February.