25.4. Where a person bound to deduct, withhold or collect an amount by virtue of a fiscal law has omitted to keep his registers and books of account in accordance with subsection 1 of section 34 or to keep such registers and books of account, as well as any vouchers necessary to verify the information contained in such registers and books of account, in accordance with sections 35.1 to 35.6, or is unable or refuses to produce such registers, books of account and vouchers to a person authorized by the Minister to examine and audit them, the Minister may issue a certificate ascertaining such omission, inability or refusal, mentioning the amount assessed; such certificate shall then make proof of the amount assessed, unless the person establishes, by documentary proof, the exact amount that should have been assessed.