Service tax exemption extended retrospectively for specified construction services, enabling refund claims subject to eligibility and certificate conditions. Insertion of three sections grants retrospective service tax exemptions for construction-related services to specified governmental or government-controlled bodies and for works on civil, educational, clinical, cultural, residential, airport and port projects under pre-cutoff contracts; each section requires refund of tax collected if exemption would have applied and confines refund claims to a short period following enactment, with airport and port exemptions conditioned on ministry certification.