  We derive precise standard model predictions for the dilepton invariant mass
and the tau energy distributions in inclusive B -> Xc tau nu decay. We include
Lambda_QCD^2/m_b^2 and alpha_s corrections using the 1S short-distance mass
scheme, and estimate shape function effects near maximal tau energy. These
results can improve the sensitivity of b -> c tau nu related observables to
beyond standard model physics.
