Service tax exemption for GSTN services applies retrospectively; refunds allowed for collected tax subject to prescribed claim timeline. The provision excludes levy and collection of service tax on taxable services provided or agreed to be provided by the Goods and Services Tax Network to Central, State or Union territory administrations for the period 28 March 2013 to 30 June 2017, and entitles persons from whom such tax was collected to refunds, subject to a claim filed within six months from the Finance Bill, 2018 receiving Presidential assent; Chapter V provisions apply retrospectively for refund processing as if continuously in force.