asked her Majesty's Government:What is the present state of the law concerning the petroleum revenue tax and allowances against abandonment costs relating to installations on the British continental shelf and how this compares with what the situation would be if the United Kingdom domestic law incorporated the provisions of the UN Law of the Sea Convention.

The costs of closing down all or part of an oil or gas field are deductible for petroleum revenue tax purposes to the extent that they are incurred for the purposes of safety or the prevention of pollution. I expect most of the cost which domestic law now requires companies to incur to be deductible. I have no reason to suppose that this position would be significantly different if domestic law incorporated the provisions of the UN Law of the Sea Convention, but those provisions are subject to rules which have not yet been laid down.