Extension of the resource rent tax from offshore oil and gas to all land-based mining activities is the centrepiece of the tax policy measures announced yesterday by the Australian government.The company tax rate will drop in two stages, falling from 30 cents in the dollar at present to 29 cents from 2013/14 and 28 cents from 2014/15.For small business the 28 cents rate will apply from 2012/13. The small business is not defined in the policy announcement but is reported elsewhere to be aimed at businesses with annual turnover of less than $2 million. Small business will also be able to write off low-value assets and some other assets in the tax year they are purchased.The surprise of the policy measures is the phased increase in the superannuation levy that all employers must pay.This will increase from nine per cent of income to 12 per cent, with the increased levy phased in over seven years from 2012.