The host of the 2022 World Cup said it expected to be short of 46.5 billion riyals ($12.77 billion) next year and that revenues were likely to fall to 156 billion riyals (42.85 billion), compared with 226 billion riyals in 2015.
The budget was calculated at an oil price of $48 per barrel, much higher than the current rate of around $35 per barrel.
Oil prices have fallen from more than $100 a barrel in July 2014 due to high output from the US and key Middle Eastern oil producers.
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Expenditure in Qatar, the world's largest exporter of liquified natural gas, is forecast to stand at 202.5 billion riyals, down from 218 billion riyals last year, state news agency QNA said.
Qatar had said it was considering some spending cuts and reducing subsidies as the International Monetary Fund urged oil-rich Gulf states to adjust heir budgets.
But the 2022 host of the one of the world's largest sporting events is planning to increase spending on major projects by 3.3 billion riyals to reach 90.8 billion riyals in 2016.
Qatar has embarked on a huge infrastructure spending splurge worth $200 billion ahead of hosting the top football tournament.
Qatar sits on 12.7 percent of the world proven reserves of natural gas, and 1.5 percent of crude oil wealth, according to US Energy Information Administration.