  Altermagnetism is a topic that has lately been gaining attention and the
RuO$_2$ compound is among one of the most studied altermagnetic candidates.
However, the survey of available literature on RuO$_2$ properties suggests that
there is no consensus about the magnetism of this material. By performing
density functional theory calculations, we show that the electronic properties
of stoichiometric RuO$_2$ are described in terms of a smaller Hubbard $U$
within DFT+$U$ than the value required to have magnetism. We further argue that
Ru vacancies can actually aid the formation of a magnetic state in RuO$_2$.
This in turn suggests that a characterization of the amount of Ru vacancies in
experimental samples might help the resolution of the controversy between the
different experimental results.
