We present a practical procedure for the evaluation of the Fermi energy in semi‐insulating (SI)GaAs from electrical measurements. This procedure makes it possible to reliably extend the determination of the major deep level (EL2) concentration, by near‐infrared absorption measurements, to SI GaAs. Employing this procedure, we showed that the EL2 concentration in Czochralski‐grown GaAs increases monotonically with increasing As/Ga ratio (throughout the conversion from SIntype to semiconductingp‐type crystals) rather than abruptly as previously proposed.