Retrospective exemption from service tax for Naval Group Insurance Fund life insurance; refunds claimable within six months. A retrospective exemption prevents levy or collection of service tax on life insurance services provided by the Naval Group Insurance Fund to Coast Guard personnel under Central Government Group Insurance Schemes for the period from 10 September 2004 to 30 June 2017, and establishes a refund mechanism for tax collected, with refund claims required within six months of the Finance Bill, 2018 receiving Presidential assent and the prior Chapter's provisions treated as having continued in force for refund purposes.