Proof of payment entitlement: credit granted on production of receipted form; alternative documentary proof required if unavailable. Allowance of credit is conditioned on presentation of Part B of the receipted Form DVAT-20; if Part B is unavailable, the dealer must furnish Part C or Part D of Form DVAT-20 supported by a certificate from the appropriate Government treasury confirming deposit and an affidavit attesting to the genuineness of those documents, failing which the Commissioner may disallow the credit.