Philippe Huguen/AFP via Getty Images EU worried migrants will shop around for best return deal The amount of financial incentive offered by EU countries varies considerably.

Financial incentive. Reward for good behavior. Gift. Bribe. Call it what you like, but payments to migrants to encourage them to return to their countries of origin are now key to Europe's migration policy. They are also creating a problem.

The amount offered in so-called assisted voluntary return payments varies considerably across the EU. Migrants in Germany, for example, can receive upwards of €5,000 in payments and in-kind assistance to leave, while those in the Czech Republic receive nothing. That has created perverse incentives, with the European Commission warning about migrants "shopping" around for the best deal.

In a communication published earlier this month, the Commission argued that the levels of cash or in-kind contributions returnees receive for leaving voluntarily should be consistent across the bloc. Member countries have officially welcomed the move but there is little sign yet of it being put into practice.

On Monday, a common return policy was discussed by EU home affairs ministers. Carmelo Abela, the home affairs minister of Malta, which holds the rotating presidency of the Council, said the current return policy is not effective. “We need to make sure that our assistance helps to boost these returns,” he said.

"The more migrants that leave voluntarily, the less have to be locked up and deported" — Commission official

Paying asylum seekers and other irregular migrants to leave might seem a politically dangerous tactic for EU members to deal with their immigration headache — particularly with nationalist movements on the rise across the Continent. But it has been adopted by most EU countries as a way to unclog their overwhelmed asylum systems. According to Commission President Jean-Claude Juncker, only a third of those whose applications to stay are unsuccessful actually leave, something he described earlier this month as "not sustainable."

In some cases, in order to receive the payment and other assistance, the migrant must agree to go voluntarily before their case has been decided. This works out cheaper for the host country in the long run than forceful deportation.

"Voluntary returns are a very important part of our return policy," a Commission official said. "The more migrants that leave voluntarily, the less have to be locked up and deported."

The Commission has called on member countries to have operational assisted voluntary return programs in place by June 1.

Last year, there were 81,575 assisted voluntary returns from Europe, according to the International Organization for Migration (IOM) — although the figures are not comprehensive. According to the most recent figures from Eurostat, there were more than 2 million irregular migrants in the EU in 2015.

But assisted voluntary return payments vary significantly between countries, and may also depend on the migrant's country of origin and their age. In February, Germany more than doubled so-called start-up money for returnees from €500 to €1,200. Including in-kind assistance, the amount a migrant receives can total €5,000 or more.

France temporarily increased its assistance in cash last year from €650 to €2,500. Austria increased its cash payments to Afghan, Nigerian and Moroccan returnees from €370 to €500 in 2016. Portugal boosted in-kind assistance from €1,500 to €2,000 earlier this year.

A review by the European Migration Network, an EU-funded expert group, found major inconsistencies in 2015. France offered up to €7,000 in payments and in-kind benefits. Norway, which is part of the Schengen area, assisted child returnees with up to €3,750 cash. Sweden paid up to €3,300 to an adult returner, while Bulgaria, Hungary and Latvia paid only €100. In Bulgaria and Poland in-kind assistance was worth up to €500. According to the IOM, the Czech Republic no longer provides any assistance. Most voluntary returnees do not receive the maximum amounts on offer.

The EU supports member countries in funding the return schemes, mainly through its Asylum, Migration and Integration Fund (AMIF). For the 2014-2020 period, it allocated €800 million from AMIF funds, adding a further €200 million earlier this year.

But the Commission now fears that the differences between member countries will lead to so-called secondary movements of migrants within Europe. "Irregular migrants could go to another country because they are given more support for their return to the country of origin," said a Commission spokesperson.

There is no explicit data on whether this actually happens, but Anne Dussart, chair of Caritas Europe Action Group on Migration, a Catholic NGO, thinks it is likely. "If one compares the nationalities of the returnees from different EU countries, it is striking that from the one EU state many more people re-enter a certain country of origin than from another," she said, adding that this could be because of the disparity between countries in the support they provide.

The Commission has a second concern: If receiving countries know that returnees from one EU country bring more money with them than those from another, "this may lead to countries of origin favoring only those returns coming from member states offering higher reintegration packages." It does not yet have evidence this is happening though.

Jacopo Barigazzi contributed to this article.