To assess uncertainties, national experts applied IPCC 2000 Good Practice Guidance on Uncertainty Management. It was decided to identify an uncertainty percentage for each sector and subdivide the uncertainties into three basic groups:

• the low uncertainty group (10-33%),
• the middle uncertainty group (33-66%),
• and the high uncertainty group (66-100%).

The low level of uncertainty is observed in "Energy" sector. There is a problem of coincidence in energy balance, particularly with natural gas, which makes uncertainty to the middle level.

The low level of uncertainty is observed in the “Industrial processes" sector. Exception is PFC emissions from aluminum production as they possess exceptional high GWP and instrumental monitoring is needed to define exact volume of PFC emissions.

The middle level of uncertainty is observed in the “Agriculture” sector. Uncertainties in methane emissions from enteric fermentation and manure management are estimated in some years as low and middle because of the lack of statistical data and possible inaccuracy in emission factors in local conditions.

The high level of uncertainty is stated in methane emissions from waste disposal on lands and domestic wastewaters because of absence of statistical data and possible inaccuracy in emission factors.

The middle level of uncertainty is estimated in the sector "Land-use change and forestry". It occurs because emission factors for different types of soils are not sufficiently researched. Besides, there are some gaps in the data on potential of national forests to absorb CO₂.

The high level of uncertainty is estimated in N₂O emissions from agricultural soils.