  We study the possible effects of TeV scale new physics (NP) on the rate for
Higgs boson decays to charged leptons, focusing on the tau tau channel which
can be readily studied at the Large Hadron collider. Using an SU(3)_C X SU(2)_L
X U(1)_Y invariant effective theory valid below a NP scale Lambda, we determine
all effective operators up to dimension six that could generate appreciable
contributions to the decay rate and compute the dependence of the rate on the
corresponding operator coefficients. We bound the size of these operator
coefficients based on the scale of the tau mass, naturalness considerations,
and experimental constraints on the tau anomalous magnetic moment. These
considerations imply that contributions to the decay rate from a NP scale
Lambda ~ TeV could be comparable to the prediction based on the SM Yukawa
interaction. A reliable test of the Higgs mechanism for fermion mass generation
via the h-> tau tau channel is possible only after such NP effects are
understood and brought under theoretical control.
