Section 21: substituted, on 1 April 2011 (applying to supplies made on or after 1 April 2011), by section 15(1) of the Taxation (GST and Remedial Matters) Act 2010 (2010 No 130).
Section 21(2)(ab): inserted, on 30 March 2017, by section 358(1) of the Taxation (Annual Rates for 2016–17, Closely Held Companies, and Remedial Matters) Act 2017 (2017 No 14).
Section 21(4B): inserted, on 30 March 2017, by section 358(2) of the Taxation (Annual Rates for 2016–17, Closely Held Companies, and Remedial Matters) Act 2017 (2017 No 14).
Section 21(5): inserted (with effect on 1 April 2011), on 2 November 2012, by section 216 of the Taxation (Annual Rates, Returns Filing, and Remedial Matters) Act 2012 (2012 No 88).