We study the changes of Bi electronic structure near T and L points of the Brillouin zone caused by doping with Sn (concentrations_0.08 at.%). Hall coefficient and magnetoresistance measurements (under magnetic field dup to 8 T) enabled calculation of magneto conductivity tensor components. The usage of quantitative mobility spectrum analysis together with the isotropic approximation for band structure allowed the estimation of Fermi level position at temperatures 10–300 K. The results have shown that Sn doping shifts the Fermi level down on the energy scale at the L point (in all temperature range) and at the T point under (primarily at low temperatures), leading to the decrease of band overlap.