In Russia, Kazakhstan and Belarus
Russia
For individuals the interest is 1/300 of the key rate a day of the debt amount (Art. 75 of the Tax Code, «НК РФ»). The debt shows as a negative balance of the Unified Tax Account (ЕНС, ENS) in your personal account. The tax office sends a demand, then may go to court and to the bailiffs.
Kazakhstan
In Kazakhstan tax not paid on time is also called arrears (tax debt); late-payment interest is charged on it.
Belarus
In Belarus, late-payment interest is charged for not paying tax on time, and the tax office may recover the debt by force.
Sources: Tax Code of the Russian Federation, part one («Налоговый кодекс РФ»), ConsultantPlus, Federal Tax Service of Russia («ФНС России»)