Facebook is the latest major corporate to bow to the increasing pressure mounting on multi-national companies to pay their fair share of tax. It will start paying tax on major advertisement revenue in the UK rather than Ireland. Google, Amazon and Apple are among other high profile companies that have been under fire for using loopholes in tax systems to avoid paying tax, by shifting profits to countries with low tax regimes. The OECD estimates that multinationals' tax avoidance is worth between 100 and 240 billion US dollars annually. The European Union has recently come out with an Anti Tax Avoidance Package saying billions of euros are lost to public budgets every year. It follows the OECD's BEPS - Base Erosion and Profit Shifting Project - which requires companies to disclose to tax authorities how much they are making and in which countries, so they can be properly taxed.So how are countries receiving these new rules? And will they mean big global corporates won't be able to shelter profits in low-or-no tax countries. Adrian Sawyer is a Professor of Taxation at Canterbury University.