20%... Unconditional offer is required for a listed company or an unlisted company with 50 or more shareholders, where a shareholder reaches 20% or where the holding is increased between 20% and 90% (subject to the exemptions in section 611 of the Corporations Act 2001).
Creep Rule.... no requirement for an unconditional offer to be made if the holding of a shareholder with more than 19% increases by less than 3% every 6 months.
-------------------------------------------------------------------------------------------------------- 90%... Compulsory acquisition of minority shareholders possible under sections 661/664 Corporations Act 2001.