  We report on a recently completed, first calculation of the full
next-to-leading order QCD corrections for heavy flavor contributions to the
inclusive structure function $g_1$ in longitudinally polarized deep-inelastic
scattering. All results are derived with largely analytical methods and retain
the full dependence on the heavy quark's mass. As a first phenomenological
application, inclusive charm production at a future electron-ion collider and
its sensitivity to the polarized gluon distribution is studied. Theoretical
uncertainties due to the residual dependence on unphysical factorization and
renormalization scales are estimated.
