The government has cut the windfall profit tax on domestically produced crude oil to zero and halved the levy on the export of diesel to Rs 0.50 per litre in line with softening international oil prices, according to an official order. The levy on crude oil produced by companies such as Oil and Natural Gas Corporation (ONGC) has been reduced to nil from Rs 3,500 per tonne ($5.8 per barrel), the order dated April 3 said.