  The twist-3 collinear factorization framework has drawn much attention in
recent decades as a successful approach in describing the data for single spin
asymmetries (SSAs). Many SSAs data have been experimentally accumulated in a
variety of energies since the first measurement was done in late 70s and it is
expected that the future experiments like Electron-Ion collider will provide us
with more data. In order to perform a consistent and precise description of the
data taken in different kinematic regimes, the scale evolution of the collinear
twist-3 functions and the perturbative higher order hard part coefficients are
mandatory. In this paper, we introduce the techniques for next-to-leading order
(NLO) calculation of transverse-momentum-weighted SSAs, which can be served as
a useful tool to derive the QCD evolution equation for twist-3 functions, and
to verify the QCD collinear factorization for twist-3 observables at NLO, as
well as to obtain the finite NLO hard part coefficients.
