Based on the guidelines given in Appendix 11 of the International Code of Nomenclature of Prokaryotes, a list in the form of a codified record of organisms of the status Candidatus must be kept by the Judicial Commission of the International Committee on Systematics of Prokaryotes in cooperation with the Editorial Board of the International Journal of Systematic and Evolutionary Microbiology (IJSEM) and published in that journal in appropriate intervals. To comply at least in part with the guidelines of Appendix 11, we earlier presented Candidatus List no. 1 that contained an inventory of Candidatus taxa compiled from the literature published until the end of 2018 [1] and Candidatus List no. 2 with names proposed in 2019 and addenda to List no. 1 [2]. Below is a record of names of Candidatus taxa proposed in 2020 and addenda to the earlier lists. Like in the earlier Candidatus Lists, we we have suggested corrections for incorrectly formed names. These changes are proposals only, and in many cases alternative corrected names are possible.