Export duty is revised once every two months and depends on international prices for Urals crude.
"The time of record high prices seems to be over. The fall in oil prices will be matched by oil export duties," said Alexander Sakovich, deputy head of the customs division within the Finance Ministry's taxation and duties department.
"Export duty could be cut by more than $50 per metric ton."
Crude export duty was raised to a record high of $237.6 per metric ton from October 1, 2006. On August 1, the figure was set at $216.4 per metric ton.
Urals is the leading blend of Russian oil, but is sold at a discount to Brent because of its relatively high sulfur content.