  Accreting T Tauri stars are observed to be less luminous in X-rays than
non-accretors, an effect that has been detected in various star forming
regions. To explain this we have combined, for the first time, a radiative
transfer code with an accretion model that considers magnetic fields
extrapolated from surface magnetograms obtained from Zeeman-Doppler imaging.
Such fields consist of compact magnetic regions close to the stellar surface,
with extended field lines interacting with the disc. We study the propagation
of coronal X-rays through the magnetosphere and demonstrate that they are
strongly absorbed by the dense gas in accretion columns. The reduction in the
observed X-ray emission depends on the field geometry, which may explain why
accreting T Tauri stars show a larger scatter in their observed X-ray
luminosity compared to non-accreting stars.
