  We explore supersymmetric theories in which the Higgs mass is boosted by the
non-decoupling D-terms of an extended $U(1)_X$ gauge symmetry, defined here to
be a general linear combination of hypercharge, baryon number, and lepton
number. Crucially, the gauge coupling, $g_X$, is bounded from below to
accommodate the Higgs mass, while the quarks and leptons are required by gauge
invariance to carry non-zero charge under $U(1)_X$. This induces an irreducible
rate, $\sigma$BR, for $pp \rightarrow X \rightarrow \ell\ell$ relevant to
existing and future resonance searches, and gives rise to higher dimension
operators that are stringently constrained by precision electroweak
measurements. Combined, these bounds define a maximally allowed region in the
space of observables, ($\sigma$BR, $m_X$), outside of which is excluded by
naturalness and experimental limits. If natural supersymmetry utilizes
non-decoupling D-terms, then the associated $X$ boson can only be observed
within this window, providing a model independent `litmus test' for this broad
class of scenarios at the LHC. Comparing limits, we find that current LHC
results only exclude regions in parameter space which were already disfavored
by precision electroweak data.
