Royalties are generated by the public performance of your music and are collected by Performing Rights Organisations (PROs) worldwide such as APRA here in Australia, and others such as BMI, ASCAP or PRS in other territories.
When considering such royalties it is important to recognise that
you are automatically entitled to 100% of the available public performance royalties upon the creation of your musical work.
It is still standard practice for many composers to maintain 100% of the public performance royalties. This would be reflected in your contracts, in the grant of rights section, via these magic seven words; “except for those rights vested in APRA…“
However, should you choose to enter a publishing agreement with a third party in the hope that they will further exploit your musical work, the absolute maximum your publisher is entitled to is 50% of this potential royalty income (and most publishing agreements are for significantly less than this). This is because in Australia
the author of a musical work is guaranteed a minimum of 50% of public performance royalties, typically called the 'Writer's Share'. This is a statutory right.
This means that no one can force you to give up this right nor falsely claim they are the author (writer) of your musical work.
This is so important that it is worth re-stating:
It doesn't matter if you have a publisher, grant a sync license for your Music, grant copyright in the Master recording or even assign copyright in the Music itself to a client, you are legally entitled to a minimum 50% share of the entire available public performance royalties. This is known as the ‘Writer’s Share’.
The remaining 50% of the whole is often referred to as the so-called 'Publisher's Share', however the name is somewhat misleading because, unless you sign an agreement to the contrary, you are entitled to all of the 'Publisher's Share'. Furthermore, the publisher is only entitled to the proportion of the 'Publisher's Share' you both agree to (should you decide that having a publisher would be to your benefit).
Most screen composers in Australia do not have fixed term publishing agreements, although individual publishing agreements per project are becoming more common. Please read here for more information on publishing.