  We derive a low-energy effective $\mathbf{k}\cdot\mathbf{p}$ Hamiltonians for
monolayer C$_{3}$N at the $ \Gamma $ and $ M $ points of the Brillouin zone
where the band edge in the conduction and valence band can be found. Our
analysis of the electronic band symmetries helps to better understand several
results of recent ab-initio calculations[1,2] for the optical properties of
this material. We also calculate the Landau level spectrum. We find that the
Landau level spectrum in the degenerate conduction bands at the $ \Gamma $
point acquires properties that are reminiscent of the corresponding results in
bilayer graphene, but there are important differences as well. Moreover,
because of the heavy effective mass, $n$-doped samples may host interesting
electron-electron interaction effects.
