Fossil fuel subsidies are significant. There are currently two ways of measuring fossil fuels subsidies. The OECD uses a bottom-up method of estimating government support to fossil fuels by identifying and quantifying individual policy measures. The IEA and the IMF data measures the gap between the end-use prices paid by fuel consumers and reference prices (i.e., a price-gap approach). The IMF information includes both undercharging for supply and environmental costs, while the IEA only includes undercharging for supply costs.
The OECD Inventory of Support Measures for Fossil Fuels documents and estimates government measures that encourage fossil-fuel production or consumption relative to alternatives. Data are updated annually and go back to 2010. The latest edition of the Inventory includes around 1,500 support measures in 51 OECD, G20, and EU Eastern Partnership economies. In addition, the OECD and the IEA produce a combined estimate of fossil fuel support over a greater number of countries.
Please also refer to the information under “Cross-sectoral and economywide”. Data sources listed therein can contain relevant information on fossil fuel subsidies.