  We present the calculation for single-inclusive jet production in
(longitudinally) polarized deep-inelastic lepton-nucleon scattering at
next-to-next-to leading order (NNLO) accuracy, based on the Projection-to-Born
method. As a necessary ingredient to achieve the NNLO results, we also
introduce the next-to-leading-order (NLO) calculation for the production of
di-jets in polarized DIS. Our di-jet calculation is based on an extension of
the dipole subtraction method to account for polarized initial-state partons.
We analyze the phenomenological consequences of higher order QCD corrections
for the Electron-Ion Collider kinematics.
