  Motivated by the recently reported excess of electron recoil events by the
XENON1T experiment, we propose low scale seesaw scenarios for light neutrino
masses within $U(1)_X$ gauge extension of the standard model that also predicts
stable as well as long lived dark sector particles. The new fields necessary
for seesaw realisation as well as dark matter are charged under the $U(1)_X$
gauge symmetry in an anomaly free way. A singlet scalar field which effectively
gives rise to lepton number violation and hence Majorana light neutrino masses
either at tree or radiative level, also splits the dark matter field into two
quasi-degenerate states. While sub-eV neutrino mass and non-zero dark matter
mass splitting are related in this way, the phenomenology of sub-GeV scale
inelastic dark matter can be very rich if the mass splitting is of keV scale.
We show that for suitable parameter space, both the components with keV
splitting can contribute to total dark matter density of the present universe,
while opening up the possibility of the heavier dark matter candidate to
undergo down-scattering with electrons. We check the parameter space of the
model for both fermion and scalar inelastic dark matter candidates which can
give rise to the XENON1T excess while being consistent with other
phenomenological bounds. We also discuss the general scenario where mass
splitting~$\Delta m$ between the two dark matter components can be larger,
effectively giving rise to a single component dark matter scenario.
