The hadronic \tau decay of a heavy charged Higgs boson, H^\pm \rightarrow \tau \nu , is considered in ATLAS. In the mass region m_H^\pm > m_t, the most relevant decay channels of the charged Higgs boson are H^\pm \rightarrow tb and H^\pm \rightarrow \tau \nu . Whereas the former suffers from large irreducible backgrounds, the latter offers a relatively clean environment with the appropriate cuts. In addition, a further suppression of the backgrounds is achieved by making use of the polarization of the \tau lepton.

PACS numbers: 12.60.Jv, 14.60.Fg, 14.80.Cp