A substantial interest, for the purposes of Australia’s foreign investment regime, is an interest of 20% or more in an Australian entity, business, or trust, held directly or indirectly by a single foreign person together with their associates. The substantial interest threshold is one of the two limbs (alongside the monetary threshold) that determines whether FIRB notification is mandatory for most non-sensitive transactions.
For national security businesses, a “direct interest” of 10% or more (or any interest with control or influence) triggers a $0 threshold notification requirement.