Burden of proof for input tax credit rests on the claimant, reinforcing claimant's evidentiary responsibility under GST. Sections 153-157 set administrative powers and evidentiary responsibilities: officers may engage experts (Section 153); the Commissioner or authorised officer may take goods samples and must provide receipts (Section 154); claimants bear the burden of proving entitlement to input tax credit (Section 155); and persons acting or intending to act in good faith under the Act are protected from suit or prosecution, including officers authorised under the Act (Section 157).