In some scenarios, it is beneficial to split your loan between a fixed interest rate loan and variable interest loan as it can save you money both the short and long term. This ultimately comes down to your financial position, the value of the property and how much cash you have available to put into an offset.
This calculator provides a high level overview of how much interest you would be paying on a split loan versus if you did not take a split loan. It does not factor any cash stored into an offset account. Using split loans is a common strategy amongst mortgage brokers for many borrowers. This calculator can help you verify the numbers that your mortgage broker puts forward to you.