In view of the recent evidence found in favor of subband mixing in coupling of confined impurity states in doped double-quantum-well structures, a variational approach employing Gaussian trial wave functions has been used to calculate the binding energies of the ground, (1s, m=0) and first excited, (2p - , m=-1) states of a hydrogenic donor associated with the mixture of subbands of a double-GaAs quantum well coupled by a layer of Ga 1-x Al x As in the presence of a magnetic field