Income tax: capital gains: if the requirements of section 126-5 or 126-15 of the Income Tax Assessment Act 1997 are satisfied, is the marriage breakdown roll-over provided by the section automatic?

Yes. Both sections 126-5 and 126-15 of the Income Tax Assessment Act 1997 apply automatically once their requirements are satisfied. The provisions are clearly expressed in this respect and contain no scope for any election to be made. Parties to a marriage breakdown cannot agree not to apply the provisions if the requirements have been satisfied.