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The atomic structure and electronic properties of the (100) surface of the Au-Si-Ho Tsai-type quasicrystalline approximant has been investigated under ultrahigh vacuum conditions. After annealing the sample between 853 K and 878 K, Au-Si-Ho(100) exhibits a (2 x 1) surface reconstruction with a topography described by large terraces separated by a single step height equal to half the unit-cell parameter. The surface appears to terminate at specific bulk planes intercepting the Tsai-type clusters at their center. The electronic density of states is dominated by the 5d states of Au below the Fermi level and by the 5d states of Ho above the Fermi level with a metalliclike Fermi edge.