FIRMS that avoid paying tax will be banned from getting lucrative UK Government contracts, Treasury Minister Danny Alexander insisted as he warned rich tax dodgers "we're coming to get you".

With the logo "fairer taxes in tough times" as the Liberal Democrat conference theme, Mr Alexander referred to how in the summer he had shut down the "scandalous situation", where thousands of public sector workers were being paid in a way that could help them avoid tax.

The situation was illustrated by the case of Ed Lester, head of the Student Loans Company, who was paid through a company without tax being deducted.

The Chief Secretary to the Treasury said he now wanted to extend the principle – that if you are being paid public money, you should pay your taxes – to the corporate sector.

"There are thousands of large firms that receive taxpayers' money to deliver a service; they do a good job helping to deliver public services.

"But I have discovered there is nothing that prevents the very small minority of firms that don't play by the rules from winning Government contracts. That is not right, that is not fair and I am determined that it comes to an end."

He added: "If you want to work for us, you should play by our rules. Taxpayers' money should not be funding tax dodgers. So I have tasked HMRC and the Cabinet Office to come up with a workable solution."

Mr Alexander told the con-ference that having announced last year he had closed loopholes to raise an additional £2 billion, he could now announce this figure had doubled to £4bn.

The newly-established Affluent Unit within HM Revenue and Customs had in less than a year raised £44 million. It would now expand its remit to focus on Britain's wealthiest 500,000 people, those individuals with a net wealth of more than £1m.

However, Stewart Hosie for the SNP said the LibDem conference promises on tax had gone "from a cynical exercise in rewriting reality to a comical one".

He said: "Danny Alexander tells tax evaders – we are coming to get you – when the number of tax inspectors has fallen by over 1500 under his watch."

The Dundee MP added: "One could say it is a tax fraud itself to promise more tax inspectors when they have been cut by such a number."