At the sixth fortnightly review, the government reduced the tax on domestically-produced crude oil to Rs 8,000 per tonne from Rs 10,500 per tonne.
The levy on the export of diesel was reduced to Rs 5 per litre from Rs 10 per litre.
The tax at the rate of Rs 5 a litre on Aviation Turbine Fuel (ATF) exports was scrapped with effect from October 2, according to a finance ministry notification issued late Saturday night.
The reduction in the tax rates follows the easing of crude oil prices in international markets.
While private refiners Reliance Industries Limited and Rosneft-based Nayara Energy are the principal exporters of fuels like diesel and ATF, the windfall levy on domestic crude targets producers like state-owned Oil and Natural Gas Corporation (ONGC) and Vedanta Limited.
India first imposed windfall profit taxes on July 1, joining a growing number of nations that tax super normal profits of energy companies. But international oil prices have cooled since then, eroding the profit margins of both oil producers and refiners.
Export duties of Rs 6 per litre (USD 12 per barrel) were levied on petrol and ATF and Rs 13 a litre (USD 26 a barrel) on diesel.
A Rs 23,250 per tonne (USD 40 per barrel) windfall profit tax on domestic crude production was also levied.
The duties were partially adjusted in the previous five rounds on July 20, August 2, August 19, September 1 and September 16 and were removed for petrol.