The UN recommends that censuses should be taken in years that end with zero or close to such years (ideally years ending with 9 and 1, respectively). Since it is impossible for all countries to agree on simultaneous censuses, the UN has organised so-called "census rounds".

For example, as part of the 2020 World Population and Housing Census Programme countries are urged to hold at least one population and housing census between 2015 and 2024. This will allow a comparison of the census results in different countries.

The 2020 census round has specific features: the COVID pandemic in 2020 led to the cancellation of censuses in many countries, including Russia.

Experts are concerned that this will make census results non-comparable with census results from previous rounds, presenting a serious challenge to statisticians globally.