Input tax credit apportionment requires periodic reversal and final reconciliation for capital goods across exempt and taxable uses. Rule 43 mandates classification of capital goods into exclusive non business/exempt, exclusive taxable, and common use; aggregates common credit ('Tc') for crediting over a five year useful life; allocates monthly credit ('Tm' = Tc / 60); apportions exempt attributable credit ('Te') each tax period using E/F or project specific carpet area ratios; requires addition of Te to output tax with interest; and prescribes final project reconciliation where Tefinal and Tcfinal determine reversals or reclaiming of excess credit, with separate computations for different tax components.