  It is well known that one cannot apply a conformal transformation to $f(T)$
gravity to obtain a minimally coupled scalar field model, and thus no Einstein
frame exists for $f(T)$ gravity. Furthermore nonminimally coupled "teleparallel
dark energy models" are not conformally equivalent to $f(T)$ gravity. However,
it can be shown that $f(T)$ gravity is conformally equivalent to a teleparallel
phantom scalar field model with a nonminimal coupling to a boundary term only.
In this work, we extend this analysis by considering a recently studied
extended class of models, known as $f(T,B)$ gravity, where $B$ is a boundary
term related to the divergence of a contraction of the torsion tensor. We find
that nonminimally coupled "teleparallel dark energy models" are conformally
equivalent to either an $f(T,B)$ or $f(B)$ gravity model. Finally conditions on
the functional form of $f(T,B)$ gravity are derived to allow it to be
transformed to particular nonminimally coupled scalar field models.
