Next-to-leading order corrections to
jet cross sections in deep inelastic scattering at HERA are
studied. The predicted jet rates allow for a precise
determination of $\alpha_s(\mu_R)$ and the gluon density
at HERA. We argue, that the ``natural'' renormalization and
factorization scale is in general set by the average $k_T^B$
of the jets in the Breit frame. Some implications
for the associated forward jet production in the low $x$
regime at HERA are discussed.