Penalty for failure to cooperate: discretionary remission allowed where voluntary disclosure and cooperation occur. Sections 18A-18B establish a penalty regime for refusal to answer questions, sign statements or furnish required information and authorize specified higher officers to impose such penalties only after giving the person an opportunity to be heard; they also empower the Commissioner to reduce, waive, stay or compound penalties where a taxpayer has made voluntary and bona fide full disclosure, cooperated in inquiries and arranged payment of tax or interest, subject to constraints including Board approval for large disclosures and finality of remission orders.