In Russia, Kazakhstan and Belarus
Russia
It is determined by a regional budget institution under Federal Law No. 237-FZ and entered in the EGRN (the Unified State Register of Real Estate). You can find it free of charge on the Rosreestr website or in an EGRN extract. If it is higher than the market value, it can be challenged with this institution or in court.
Belarus
In Belarus the cadastral value is determined for land plots; land tax is calculated from it.
Sources: Rosreestr, the Federal Service for State Registration, Cadastre and Cartography («Росреестр»), Federal Tax Service of Russia («ФНС России»)