Waiver of interest and penalty: electronic application and payment procedure to conclude GST demands and modify liabilities. Section 128A procedures require eligible persons to apply electronically (FORM GST SPL 01 or SPL 02) and to pay the tax demanded-payments must be credited to the Electronic Liability Register or converted via FORM GST DRC 03A when applicable. Mixed period or erroneous refund demands require full payment for the relevant period before filing. Applications have prescribed filing timelines and documentary evidence of withdrawal or intimation of appeals. The proper officer issues notices (FORM GST SPL 03), allows replies (FORM GST SPL 04), and must issue acceptance (FORM GST SPL 05) or rejection (FORM GST SPL 07) within specified time limits, failing which applications are deemed approved; non payment within prescribed periods voids any waiver.