Using the variational density-functional perturbation theory, we investigate the dynamical and dielectric properties of tetragonal zirconia (t-ZrO2). We obtain the phonon frequencies at the center of the Brillouin zone, the Born effective charge tensors, and the dielectric permittivity tensors. For all these quantities, a comparison is made with the related values in the cubic phase. The Born effective charge tensors are found to be quite anisotropic. The calculated phonon frequencies present a better agreement with the infrared and Raman experimental values than previous theoretical calculations. We propose symmetry assignments that solve the contradictions existing in the literature. The electronic and static dielectric permittivity constants are in relatively good agreement with experimental values. We perform a detailed analysis of the contribution of the various infrared-active modes to the static dielectric permittivity and explain its strong anisotropy.