The electronic structure of uranium and plutonium nitrides in ambient conditions and under pressure is investigated using the LDA + U + SO band method taking into account the spin–orbit coupling and the strong correlations of 5f electrons of actinoid ions. The parameters of these interactions for the equilibrium cubic structure are calculated additionally. The application of pressure reduces the magnetic moment in PuN due to predominance of the f6 configuration and the jj-type coupling. An increase in the occupancy of the 5f state in UN leads to a decrease in the magnetic moment, which is also detected in the trigonal structure of the UNx β phase (La2O3-type structure). The theoretical results are in good agreement with the available experimental data.