From Table it can be seen that the density fitting errors in the reaction energies are typically small, even when using the cc-pVnZ/JKFit auxiliary sets. However, in applications where high-accuracy is required these errors may be significant. It is also evident that the density fitting errors for cc-pV(5+d)Z with cc-pV5Z/JKFit are essentially the same as those for cc-pV(Q+d)Z with cc-pVQZ/JKFit, and the MAX density fitting error of 0.