  Kaluza-Klein reductions of low energy string effective actions possess a
continuous $O(d,d) $ symmetry. The non-geometric elements of this group,
parameterized by a bi-vector $\beta$, are not inherited from the symmetries of
the higher-dimensional theory, but constitute instead a symmetry enhancement
produced by the isometries of the background. The realization of this
enhancement in the parent theory was recently defined as $\beta$ symmetry, a
powerful tool that allows to avoid the field reparameterizations of the
Kaluza-Klein procedure. In this paper we further explore this symmetry and its
impact on the first order $\alpha'$-corrections. We derive the $\beta$
transformation rules from the frame formulation of Double Field Theory (DFT),
and connect them to the corresponding rules in the Metsaev-Tseytlin and
Bergshoeff-de Roo supergravity schemes. It follows from our results that
$\beta$ symmetry is a necessary condition for the uplift of string
$\alpha'$-expansions to DFT.
