An analytical approach based on the Cagniard-DeHoop (CdH) technique is applied to derive the time-domain (TD) partial-inductance retarded partial coefficient pertaining to two adjoining brick elements. It is demonstrated that the CdH approach leads to closed-form TD expressions that are easy-to-implement and can be evaluated relatively quickly within any prescribed accuracy. Accordingly, the novel TD formulas introduced in this article can be used to supplement standard (quasi)static partial element equivalent circuit (PEEC) models, thereby improving their stability behavior for high-frequency applications for which the (quasi)static approximation ceases to be valid. Illustrative numerical examples are presented.