We investigated the atomic structure of nitrogen (N) at the SiO2/SiC(1-100) interface after nitric oxide annealing via X-ray absorption spectroscopy (XAS) and theoretical simulations without SiO2 films. The peak shapes and energies of the observed and simulated spectra were found to be in agreement, indicating that the N-containing site could be the substitutional C site at 1000 °C and 1150 °C. N atoms can, however, be incorporated in low symmetry sites at 1300 °C. XAS analysis can distinguish between the N-containing sites at the SiO2/SiC interface.