The single-inclusive cross-section for jet production in deep inelastic e-p scattering (DIS) at HERA is measured for photon virtualities Q^2 between 5 and 100 GeV^2, differentially in Q^2, in transverse jet energy E_T, in E_T^2/Q^2 and in pseudorapidity eta_LAB. In most of the phase space these data are well described by QCD calculations in next-to-leading order (NLO) using a renormalization scale mu_R=E_T. Significant discrepancies are observed only for jets in the proton beam direction with E_T below 20 GeV and Q^2 below 20 GeV^2.