Almost all broker commission in Australia flows from lender to aggregator to broker, and the aggregator takes its fee out of that flow. Under a percentage model the aggregator keeps a slice of every upfront and trail payment, commonly leaving the broker 70% to 90% depending on volume and tenure. Under a flat-fee model the broker receives 100% of commission and pays a fixed monthly amount for the aggregator's services.
The split shows up on the RCTI as the difference between the lender payment column and the commission paid to the broker. It is easy to overlook, and it materially changes what a book is worth: a buyer values the trail the broker receives, not the gross the lender pays.
Comparing aggregators means comparing splits on the same book. A 5% difference in the trail split on $72,000 of gross trail is $3,600 a year, which over a decade is worth more than most software fees.