  We investigate the influence of the tachyonic instability on the Schwinger
effect in Higgs inflation model.In this work we identify the standard horizon
scale $ k_{H}=aH $ and the tachyonic instability $ k_{H}=aH|\zeta| ,
\zeta=\frac{{I}^{\prime}\left(\phi\right)\dot{\phi}}{H} $.This is the horizon
scale in which the given Fourier begins to become tachyonically
unstable.Influence of this scale appears by vanishing electromagnetic field
energy density and energy density of created charged particles due to the
Schwinger effect at the very beginning of inflation but does not alter
conclusions of our previous work in
Refs.\cite{Kamarpour:2022,Kamarpour:2023-I}.We use two coupling functions to
break conformal invariance of maxwell action.The simplest coupling function $
I\left(\phi\right)=\chi_{1}\frac{\phi}{M_{p}} $ and a curvature based coupling
function $ I\left(\phi\right)=
12\chi_{1}e^{\left(\sqrt{\frac{2}{3}}\frac{\phi}{M_{p}}\right)}\left[\frac{1}{3M_{p}^{2}}\left(4V\left(\phi\right)\right)+\frac{\sqrt{2}}{\sqrt{3}M_{p}}\left(\frac{dV}{d\phi}\right)\right]
$ where $V\left(\phi\right) $ is the potential of Higgs inflation in
Refs.\cite{Kamarpour:2022,Kamarpour:2023-I}.In fact, we find that only at the
very beginning of inflation both energy densities of electromagnetic field and
created charged particles vanish due to effect of tachyoinc instability.
