Epistemic logic programs constitute an extension of the stable model semantics to deal with new constructs called "subjective literals." Informally speaking, a subjective literal allows checking whether some objective literal is true in all or some stable models. However, its associated semantics has proved to be non-trivial, since the truth of subjective literals may interfere with the set of stable models it is supposed to query. As a consequence, no clear agreement has been reached and different semantic proposals have been made in the literature. In this paper, we review an extension of the well-known splitting property for logic programs to the epistemic case. This "epistemic splitting property" is defined as a general condition that can be checked on any arbitrary epistemic semantics. Its satisfaction has desirable consequences both in the representation of conformant planning problems and in the encoding of the so-called subjective constraints.