S. 147 : Reassessment-After the expiry of four years-Referral fees to doctors for referring-Allowed in the course of assessment proceedings-Change of opinion-Reassessment notice is not valid [S. 37(1), 148, Medical Council (Professional Conducts, Etiquettes and Ethics) Regulation Act, 2002 Regulations, 6.4, 6.8 and 8.1 s Art. 226]