Gapping in embedded environments may occur in two configurations: (i) the whole coordination containing both conjuncts is embedded (= embedded gapping, EG), (ii) the second (i.e. elliptical) clause is embedded within its own conjunct (= single conjunct embedded gapping, SCEG). Languages seem to differ in their restrictions on these two structures: EG in some languages does not allow for a complementizer in the elliptical conjunct, while it does in other languages. SCEG is outright unacceptable in some languages but acceptable in other languages. Overall, languages seem to fall into two groups such that one group allows a complementizer in the elliptical conjunct of EG and generally allows SCEG, whereas the other group allows neither. We present four experiments in Spanish on the acceptability of the complementizer que ‘that’ in the elliptical conjunct in EG. Our results suggest that que in Spanish EG is overall subject to similar restrictions as SCEG gapping: There are different degrees of degradation depending on the (type of) embedding verb without outright unacceptability. While the relevant property has been argued to be factivity for SCEG, we argue that it is not the factivity of the embedding verb as such that drives acceptability, but assertion embedding. We outline a theoretical proposal building on existing accounts of structural ambiguity in gapping, the truncation of complement CPs under some verbs including factives, and the general flexibility of the semantic/pragmatic categories factivity and assertion.