We consider the factorization of transverse momentum-dependent azimuthal asymmetries in semi-inclusive DIS (SIDIS) and Drell-Yan, which appear at the first subleading power in the expansion for small transverse momentum. These observables feature an intricate all-order resummation structure common to many applications of SCET at subleading power. In addition, and perhaps more importantly, they provide access to nonperturbative higher-point quark-gluon-quark (QGQ) correlation functions in the nucleon or in the fragmentation cascade. In this talk I discuss the role of soft contributions that give rise to a distinct term present only in SIDIS factorization theorems. Interestingly, the relevant soft functions are intricately connected to those appearing in multi-differential threshold factorization, allowing us to pin down their all-order structure. This plays a crucial role for a finite renormalized treatment of the collinear QGQ correlators.