A compact solvmanifold of completely solvable type, i.e. a compact quotient
of a completely solvable Lie group by a lattice, has a K\"ahler structure if
and only if it is a complex torus. We show more in general that a compact
solvmanifold M of completely solvable type endowed with an invariant complex
structure J admits a symplectic form taming J if and only if M is a complex
torus. This result generalizes the one obtained in [7] for nilmanifolds.Comment: 7 pages; to appear in Annali della Scuola Normale Superior