The crude oil duty, a major factor in the financial results of Russia's oil companies, stands at $365 per tonne in March.
The final oil export duty for April is based on the seaborne Urals price from Feb. 15 to March 14 inclusive.
Finance Ministry official, Alexander Sakovich, told Reuters on Tuesday the average price for that period was $108.16 per barrel, up from $95.79 in the previous timeframe. Urals is now trading at $109 per barrel.
Reuters calculations, based on customs tariff regulations and the average oil price estimate, show the April export duty is therefore likely to be set at $423.7 per tonne.
This would be the duty's second-highest level since it reached a record $495.9 in August and September 2008, when oil prices surged to almost $150 per barrel.
The rate is officially announced by the government at the end of each month. The April duty was slightly below the $424-$426 range forecast on March 10, four days before the end of the monitoring period.
The export duty on crude from new fields in East Siberia and the Caspian Sea, which enjoy a lower rate than Russian crude from other production areas, will rise to $191 tonne, up from $150.4 in March.
The government plans to annul the lower export fee for the fields starting from May.
The duty on light refined fuels, such as gasoline, is to rise to $283.9 per tonne compared to $244.6 per tonne in March. The duty on heavy fuels will rise to $197.9 per tonne, up from $170.4 per tonne this month.