Experimental measurements of the
transverse momentum of Drell-Yan lepton pairs
are sensitive to non-perturbative physics associated with the
intrinsic parton transverse momentum $k_T$.
We discuss recent determinations of intrinsic $k_T$
in the context of transverse momentum dependent (TMD)
parton branching calculations and collinear parton-shower Monte Carlo
generators. We illustrate
the influence of the soft-gluon resolution scale and the
non-perturbative Sudakov region on the intrinsic $k_T$
extraction. We emphasize the relevance of the correct treatment of
correlated uncertainties between different transverse momentum bins
in TMD fits and present an
application to the determination of the intrinsic $k_T$ in the
forward rapidity region.

