At the outbreak of a virus, data on cases is sparse and commonly severe cases, with a higher probability of a fatal resolution, are detected at a larger rate than mild cases. In addition, in an under-sampling situation, the number of total cases is under-estimated leading to a biased case fatality rate estimation, most likely inflating the virus mortality. In this communication, we present a method to estimate the sub-report in a country that accounts for both the delay time between symptoms onset to death and the country’s demographics. The method is based on the comparison of the corrected case fatality rate (CFR) of the target country with the one of a benchmark country. Using reported data from Instituto Nacional de Salud up to December 28, we utilize our method to provide a comprehensive estimate of the Covid-19 sub-report in Colombia, its regions and some of its cities during 2020.