Curbs on in-work benefits for EU citizens are unlikely to result in a large reduction in migration from the bloc to the UK, according to a new report.
Measures to restrict access to welfare formed a key plank of David Cameron's deal on Britain's relationship with Brussels.
In analysis published on Wednesday, experts said a "large majority" of recent EU migrants are not claiming benefits of any kind.
Available figures suggest that roughly 10 to 20% of recent arrivals from EU countries were receiving tax credits - which are usually paid to those who are working but have low incomes - in early 2014, according to the study by the Migration Observatory at the University of Oxford.
Under the agreement struck by the Prime Minister earlier this year, Britain would be able to apply for a seven-year "emergency brake" under which new migrants will only receive the right to claim in-work benefits gradually over the course of four years.
The new report said the impacts of proposed benefits restrictions are likely to be "concentrated on a small share of families with children" - in particular minimum-wage workers with children and those in families without two full-time earners.
It said: "Because the impacts of in-work benefits restrictions are concentrated on a small share of newly arriving families, it is unlikely that they would lead to a large reduction in EU migration to the UK."
There is "no direct evidence" on whether welfare has acted as a "magnet" encouraging migrants to come to the UK, according to the study.
It went on: "Among those who do receive benefits, it is not known whether the availability of benefits was an important factor. Some would presumably have moved to the UK for higher wages or better job opportunities even if these benefits had not been available.
"It is also possible that some individuals or couples would increase their working hours in order to make up for lost benefits income.
"As a result, the number of people whose initial migration decision might be affected by the immediate availability of tax credits is likely to be a small share of the total suggesting that the proposed benefits restriction is unlikely to lead to a dramatic reduction in EU immigration to the UK."
Researchers also said that if the National Living Wage increases families' incomes, this will reduce in-work benefits entitlements without restrictions on welfare eligibility.
Immigration is one of the key battlegrounds in the debate ahead of the EU referendum next month. Net migration from the bloc was running at 172,000 in the year to September.
EU migrants are less likely to claim out-of-work benefits but more likely to claim in-work benefits compared to those born in the UK, according to the Migration Observatory.
It said that 19% of recent arrivals from the European Economic Area reported receiving a state benefit in their own right last year, a share that falls to 13% if child benefit is excluded.
Madeleine Sumption, Director of the Migration Observatory, said: "Looking at reliance on welfare benefits overall, migrants from EU countries are actually not very different to people born in the UK."
She added: "A large majority of recent EU migrants are not claiming benefits of any kind.
"That means that most migrants to the UK would not be affected by proposed changes to the welfare system.
"That said, some families with children would stand to lose several thousands in tax-credit income, and would still be considerably worse off even if higher minimum wages increase their incomes over the next few years."
David Cameron's official spokeswoman said: "We have been clear that with the measures that the Prime Minister secured in February, we are ending the culture of getting something for nothing.
"When you look at some of the pull factors for migration, the fact that people can come here and from day one claim benefits is a factor we think it is right to address and the changes we have introduced will allow us to do that."
Former cabinet minister Iain Duncan Smith, who is backing Brexit, said: "These damning statistics confirm that the Prime Minister's very limited renegotiation will have no impact on migration.
"The only way to take back control of our borders is to Vote Leave on 23 June."