Net proceeds calculation: audit certificate is final and law may prescribe payment, adjustment and collection procedures. Net proceeds means tax or duty receipts reduced by the cost of collection; net proceeds attributable to any area are to be ascertained and certified by the Comptroller and Auditor General, whose certificate is final. Parliament by law, or the President by order where proceeds are assignable to a State under this Part, may prescribe methods for calculation, timing and manner of payments, inter year adjustments, and incidental or ancillary matters.