The default income growth rate is at 3% until Age 35, 2% from Age 36 to 50 and 1% after Age 50.
The reason of using this income growth rate is to ensure that the income growth are not too optimistic during the projection, as most people might find it challenging to maintain income growth after a certain age.
To customise the default income growth rate for gross incme, please click to the gross income, and look for the "Additional Settings"