Bond angle of $\mathrm{PH}_{4}^{+}$is more than that of $\mathrm{PH}_{3}$ as in $\mathrm{PH}_{3}$ due to greater lone pair-bond pair repulsions than the bond pair-bond pair repulsions, the tetrahedral angle decreases from $109^{\circ} 28^{\prime}$ to $93.6^{\circ}$ and has a pyramidal structure. In $\mathrm{PH}_{4}^{+}$, there are four bond pairs and no lone pair and due to the absence of lone pair-bond pair repulsions and presence of four identical bond pair-bond pair interactions $\mathrm{PH}_{4}^{+}$has tetrahedral geometry with bond angle $109^{\circ}$.