  Strata of exact differentials are moduli spaces for differentials on Riemann
surfaces with vanishing absolute periods. Our main result is that classes of
closures of strata of exact differentials inside the moduli space of
multi-scale differentials lie in the divisorial tautological ring. By relating
exact differentials to rational functions we obtain a new proof that classes of
Hurwitz spaces are tautological and a new method for computations.
