We have designed a sequence of flexible Gaussian-type basis sets for electric property calculations on the azide ion. These basis sets range from [7s5p2d] to [7s5p5d3f2g] size. We have analyzed the performance of these basis sets on calculations of the quadrupole (Θ), hexadecapole (Φ) moment, the mean (α¯) and the anisotropy (Δα) of the dipole polarizability at the self-consistent field (SCF), second-order Møller–Plesset perturbation theory (MP2) and B3LYP levels of theory. Our evaluation of the quality of these purpose-oriented basis sets bears on their overall performance on the {Θ,Φ,α¯,Δα} collection of properties. Our best values for each property at MP2/[7s5p5d3f2g] are: Θ=-8.5953ea02, Φ=-7.50ea04, α¯=41.74 and Δα=38.24e2a02Eh-1.