The effect of thermal treatments in nitric oxide (NO) on the paramagnetic defects at the 4H-SiC/SiO(2) interface are analyzed by EPR in oxidized porous samples. The results on ultrathin thermal oxides show that the NO treatment at 1000 degrees C is insufficient for an efficient reduction of the two dominant paramagnetic interface defects: P(bC) centers and carbon clusters. From the NRA and XPS analysis of bulk samples treated under the same conditions we attribute the weak effect to the low nitrogen concentration of only 1% at the interface.