An offset account is a bank account that is linked to your home loan. The balance of the account is used to offset the balance of your home loan and reduces the amount of interest you get charged. This means every dollar you keep in your offset account can help you save money on your home loan.
For example, if you have a $400,000 home loan and $20,000 in your offset account, you'll only be charged interest on your home loan on a balance of $380,000.