  The Two-Higgs Doublet Model (2HDM) is a well understood alternative to the
Standard Model of particle physics. If the new particles included in the 2HDM
are at an energy scale much greater than the weak scale, the theory can be
matched to the Standard Model Effective Field Theory (SMEFT). We compute for
the first time the complete one-loop matching at dimension-6. We compare its
numerical impact with that of tree-level matching at dimension-8 by performing
a global fit to single Higgs and precision electroweak measurements, and we
emphasize the importance of comparing one-loop SMEFT results with corresponding
one-loop results in the full 2HDM model. In the SMEFT, we consider the relative
importance of both one-loop matching and the inclusion of renormalization group
evolution. Our results demonstrate the necessity of studying the impact of
various expansions to quantify the uncertainties of the SMEFT matching.
