Companies found guilty of aggressive tax avoidance will be banned from bidding for major government contracts, under new rules published by the Treasury. Firms and individuals bidding for contracts will be required to declare whether their tax returns have been rejected because of involvement in a tax avoidance scheme. And companies will also have to sign a clause allowing departments to terminate the agreement if they are later found to have breached tax compliance obligations...The move comes after controversy over the tax affairs of multinational companies including Starbucks, Amazon and Google, though there is no suggestion these firms would fall foul of the new arrangements.