Bihar GST rules: composition levy, electronic registration, valuation, ITC rules, invoicing, returns, refunds and appeals. Rules establish the procedural framework for Bihar GST: composition levy (intimations, eligibility, rates, withdrawal), electronic registration/enrolment (forms, verification, provisional migration), valuation methods (open market, like kind, cost, residual, special cases), detailed input tax credit rules (documentary basis, distribution by ISD, attribution and annual reconciliation, capital goods treatment), mandatory tax invoice/challan formats and electronic returns, matching and ledger mechanics, refund formulas, audit and appeal/advance ruling procedures.