  The UV to X-ray continuum of active galactic nuclei (AGN) is important for
maintaining the ionisation and thermal balance of the warm absorbers (WAs).
However, the spectra in the sensitive energy range $\sim \,13.6 -300 \ev$ are
unobservable due to Galactic extinction. Moreover, many AGN show soft X-ray
excess emission of varying strength in the $0.1-2\kev$ band whose origin is
still highly debated. This soft-excess connects to the UV bump in the
unobserved region of $13.6 -300 \ev$. Here we investigate the effect of the
assumed physical model for the soft-excess on the flux of the unobserved part
of the spectrum and its effect on the WA properties. We perform a case study
using the \xmm{} observations of the bright Seyfert 1 galaxy IRAS 13349+2438
with WA features. The two different physical models for the soft excess:
blurred Compton reflection from an ionised disk, and, optically thick thermal
Comptonisation of the disk photons, predict different fluxes in the unobserved
energy range. However the current X-ray data quality does not allow us to
distinguish between them using derived WA parameters. This, in turn, implies
that it is difficult to determine the origin of the soft-excess emission using
the warm absorber features.
