Nigel Farage has said his is the only party in the General Election with a "credible plan for immigration".
Launching UKIP's Believe In Britain manifesto at a hotel in Thurrock, Essex, the party leader said the only way Britain could regain control of the issue was by leaving the EU.
He said: "We want our country back and then and only then can we actually control our borders."
The party is also promising to limit work visas for skilled immigrant to 50,000 and introduce an Australian-style immigration system, which would see fewer unskilled people entering the country.
He said this would ease pressure on schools and doctors' surgeries.
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The UKIP leader also offered a £18bn tax giveaway, saying it was all paid for. Like the Tories, he promised people on the minimum wage should not pay income tax.
He said threshold for paying the 40p rate of income tax should be £55,000 and there should be a new 30p rate between £43,500 and £55,000.
He attempted to put the Tories under pressure with a pledge to "substantially" increase defence spending, committing to spending more than 2% of GDP by 2020.
The measures are likely to be seen as a statement of intent to the Tories over what UKIP will demand if it is to help David Cameron to another five years in power.
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Mr Farage also said UKIP would push for guaranteed civilian jobs for soldiers after 12 years of service and there would be no income tax for those abroad on active service. They would also build a military hospital.
He denied "putting out feelers" for discussions on a coalition with the Tories and when asked if removing Mr Cameron would be key to any deal he said: "If I was a Conservative I'd want to get rid of David Cameron."
In an attempt to persuade voters UKIP is a serious proposition, the spending pledges in the party manifesto have been verified by the Centre for Economics and Business Research.
The key red line for any Conservative coalition for Mr Farage's party is a referendum on Britain's EU membership.
UKIP insists there should be one "as soon as possible", while Mr Cameron has promised a vote only by the end of 2017.
Mr Farage dismissed his party's 2010 manifesto as "486 pages of drivel" and admitted he had not read it before it was published.
However, he said he had "read, absorbed and understood" the 2015 version.
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Mr Farage spoke briefly at the manifesto launch before handing over to Deputy Party Chairman Suzanne Evans, who wrote the manifesto and gave details about its policies.
UKIP has been criticised for being a spent force, after its surge in the local and European elections last year when Mr Farage said the party could hold the "balance of power" at the General Election.
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However, UKIP could still influence who gets into Number 10 as they have ruled out a coalition with Labour.
The party launched its manifesto an hour after the Lib Dems, also potential kingmakers.
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