  We re-examine spontaneous $\cp$ violation (SCPV) at the tree level in the
context of the next-to-minimal supersymmetric standard model (NMSSM) with two
Higgs doublets and a gauge singlet field. We analyse the most general Higgs
potential without a discrete $Z_3$ symmetry, and derive an upper bound on the
mass of the lightest neutral Higgs boson. We estimate $\epsi_K$ by applying the
mass insertion approximation, finding that in order to account for the for the
observed $\cp$ violation in the neutral kaon sector a non-trivial flavour
structure in the soft-breaking $A$ terms is required and that the upper bound
on the lightest Higgs-boson mass becomes stronger. We also discuss the
implications of electric dipole moments of the electron and the neutron in SUSY
models with SCPV.
