Immigrants with children and elderly relatives may have to pay a special levy to help to fund public services, under proposals to be published in a Green Paper today.

The money would go into a British trust fund as part of a package of proposals for “earned” citizenship aimed at encouraging applicants for British passports to contribute to society. It is estimated that such a fund could raise up to £15 million a year.

A document leaked to Channel Four News states: “Money for the British trust fund will be raised through increases to certain fees for immigration applications, with migrants who tend to consume more in public services — such as children and elderly relatives — paying more than others.”

The Green Paper also contains a proposal that immigrants who have worked in Britain for five years be put on probation for an additional year before they can become full British citizens.

The document says that this would be to “incentivise immigrants to make the commitment to becoming British citizens and fully integrate into society”.

A Home Office spokesman said last night: “We are not commenting before the Green Paper is published.”

Gordon Brown has already suggested that applicants should be asked to undertake community or voluntary work as a way of introducing them to British institutions and people.

Ministers have rejected a points-based system for citizenship or fast-tracking applicants to a passport. They are, however, looking at barring people from becoming citizens if they have been convicted of a serious criminal offence.

The existing citizenship requirement is that a person must have lived in Britain for five years, passed a test in English and demonstrated a knowledge of life in Britain.

Before he became Prime Minister Mr Brown said: “In any national debate it is right to consider asking men and women seeking citizenship to undertake some community work in our country or something akin to that which introduces them to a wider range of institutions and people in our country prior to enjoying the benefits of citizenship.”

Liam Byrne, the Immigration Minister, who has been drawing up the proposals, said that the message had to be that becoming a British citizen was not something that was simply handed out but should be earned.

In a recent speech he said that Britons had made clear that they thought newcomers should pay taxes and that no favours should be given to the rich.

“I asked people whether successful migrants — like high-earning footballers or surgeons — should get ahead faster. I got a pretty blunt answer. Treat everyone the same. Just make sure no one’s dodging their dues.”

He added that people wanted applicants to obey British laws. “When an offence is serious, I am afraid we do want to show newcomers the exit door,” Mr Byrne said.

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