We examine the nature of RX J0806.3+1527 and show that it is possible to reconcile the observed period decrease and X-ray luminosity with the transfer of mass between two white dwarfs provided that : either the system is ( i ) still in the early and short-lived ( \lesssim 100 yr ) stages of mass transfer due to atmospheric Roche-lobe overflow , or ( ii ) in a standard , long-term , quasi-stationary mass-transfer phase that is significantly ( \sim 90 % ) non-conservative and the conversion of accretion energy to X-rays is quite inefficient .
In either of the two cases and for a wide range of physical parameters , we find that orbital angular momentum is lost from the system at a rate that is a factor of a few ( \lesssim 4 ) higher than the rate associated with the emission of gravitational waves .
Although the physical origin of this extra angular momentum loss is not clear at present , it should be taken into account in the consideration of RX J0806.3+1527 as a verification Galactic source for LISA .