  In this paper we study the problem of gauge invariance of the first order
transition amplitudes in de Sitter QED in Coulomb gauge. We consider the gauge
transformations which preserve the Coulomb gauge, that contain the gradient of
the gauge function. The final results prove that the first order transition
amplitudes do not change at a gradient transformation of the vector potential
because the only allowed transformation is $\Lambda=0$. Our results suggest
that the remarks made in the comment by Nicolaevici and Farkas {\em Phys. Rev.
D} \textbf{95}, are not directly applicable to the results in our paper since
their proposed gauge transformations do not preserve the Coulomb gauge.
