Project the recurring trail commission earned on a single Australian home loan as the principal amortises. Enter the loan amount, interest rate and term, then the lender's trail rate (typically 0.15% p.a. of outstanding balance, paid monthly). The calculator returns Year 1 trail income, cumulative trail over the projection horizon, the year-by-year trail curve, and an optional 10% GST gross-up if the broker is GST-registered. Useful for brokers sizing the lifetime value of a single deal, owners sense-checking aggregator-reported trail figures, or new brokers learning how trail compounds (and decays) over the life of a loan.