When is a tax not a tax? Apparently, when it is a levy, except it seems sometimes a levy is not a levy either. That was the coalition's contention at Parliament today as it pushes ahead with plans to build a new liquefied natural gas import facility - funded by a charge levied on the electricity companies. Labour has labelled it a "gas tax" which will drive up power bills - but the government insists it will actually reduce them. Acting political editor Craig McCulloch reports.