The short answer
Yes. Mortgage broking is a taxable supply, so a broker who is registered for GST receives commission plus 10% GST on top, and remits that GST to the ATO through the BAS. The figure that is your commission — the one to record as revenue and the one a buyer values your book on — is the GST-inclusive amount. The GST inside it is a liability you are collecting on the ATO's behalf, not a deduction from what you earned.
If that sounds like an accounting footnote, look at what it does to a number: an ex-GST figure is the inclusive figure divided by 1.1, so booking ex-GST records about 9.1% less than the commission you were actually paid. On a book paying $150,000 a year, that is $13,600 of trail that exists on the lender's statement and nowhere in your records.
Why the statement shows it twice
Aggregators issue commission on a recipient-created tax invoice (RCTI) — you are the supplier, they raise the invoice on your behalf — and an RCTI has to show the GST component. So the same trail run appears as, for example, Trail (GST Excl) beside Trail (GST Incl), or COMMISSION beside COMMISSION_INC_GST, with a separate GST or GST Amount column carrying the tax line itself. The column names differ by platform; the layout does not. The aggregator report guides show where each pair sits on AFG, Connective Mercury, MyCRM and Salestrekker exports.
Three columns, and only one of them is your commission:
| Column | What it is | Book it as |
|---|---|---|
| Commission inc GST | What the lender paid, in full | Revenue — this is the commission |
| Commission ex GST | The same amount with the tax stripped out | Not revenue. A working figure only |
| GST / GST amount | The tax line, 1/11th of the inclusive figure | A liability. Never an income column |
The mistake that costs 9%
Most bookkeeping errors here are not conceptual. They come from a spreadsheet or an import that grabbed the wrong column — usually whichever one came last in the file, because that is what a naïve column-matcher keeps. It looks right. Every row has a plausible number. Nothing flags it. The error only surfaces months later as a BAS that does not reconcile, or at the point of a sale when a buyer's due diligence re-adds the trail from statements and finds it 9% higher than the vendor's own figure — which, from the buyer's side of the table, is not a pleasant surprise, it is a data-quality question.
TrailScope's import handles this by ranking competing columns: when both figures are present it takes the inclusive one as the commission and keeps the ex-GST value beside it as the net, so the GST component can be reported without ever having been the headline number. A standalone GST column is recognised as a tax line and kept out of the amount fields entirely. If a book was imported before that rule existed, a correction pass re-reads the original statement and shows every row it would change before it changes anything — because rewriting a recorded commission is a financial edit, not a tidy-up.
Not registered for GST?
A broker below the registration threshold who has not registered does not charge GST and is paid the ex-GST amount only — there is no inclusive figure to book, and the "inc GST" column on the statement is not money you receive. That is the one situation where the exclusive column is the right one. It is also the reason the trail commission calculator carries a GST toggle rather than assuming: the same loan pays a registered broker 10% more in cash than an unregistered one, and the projection should say so.
Whether to register once you are near the threshold is a question for your accountant. Most established brokers are registered, because commission volume passes the threshold quickly and because an unregistered broker cannot claim input credits on their own costs.
What this does to a valuation
Trail books are valued as a multiple of net annual trail — net of the aggregator split, but GST-inclusive. A vendor who has been booking ex-GST walks in with a trail figure 9% low, and every multiple applied to it inherits the shortfall: at 2.4× on $150,000, the gap is roughly $33,000 of sale price. The valuation guide covers the other levers; this one is simply arithmetic, and it is the easiest of them to fix before you go to market.
A checklist
- Find the inc-GST column on your statement and confirm your records match it, not the ex-GST one, for the last three months.
- Check that your GST column has never been imported as income — it will show as a third, smaller "commission" line if it has.
- If the figures were recorded ex-GST, correct them from the source statements rather than multiplying by 1.1 — clawbacks and adjustments do not always carry GST the same way.
- Value the book on the inclusive figure, net of split. Say so in the information memorandum.
This guide describes how commission statements are laid out and how the figures relate. It is not tax advice. GST registration, BAS treatment and the handling of clawbacks and adjustments are matters for your accountant.
Related reading
- Trail commission calculator — the same projection with GST added or excluded, side by side.
- How to value a trail book — why a book valued off ex-GST trail reads 9% light.
- The aggregator report guides — where the two GST columns sit on each platform's statement.
FAQ
Is mortgage broker trail commission subject to GST?
Yes. Broking is a taxable supply, so a GST-registered broker receives commission plus 10% GST and remits the GST through the BAS. The GST-inclusive figure is the commission; the GST inside it is a liability, not a reduction.
Which column on the aggregator statement is my commission?
The inclusive one — typically labelled Trail (GST Incl), Commission inc GST or similar. The ex-GST column is the same amount with the tax removed, and a separate GST column is the tax line itself. Only the inclusive figure is revenue.
How much does booking ex-GST understate my trail?
By about 9.1%. The ex-GST amount is the inclusive amount divided by 1.1, so recording it as your commission drops roughly one-eleventh of what you were paid.
Does this affect what my trail book is worth?
Directly. Books are valued as a multiple of net annual trail, GST-inclusive. Trail recorded ex-GST enters the valuation 9% low and every multiple applied to it inherits the gap — tens of thousands of dollars on an ordinary book.
What if I am not registered for GST?
Then you are paid the ex-GST amount and there is no inclusive figure to book. The inc-GST column on the statement is not money you receive. That is the one case where the exclusive column is correct.
How does TrailScope handle the two columns?
When both are present it imports the inclusive figure as the commission and keeps the ex-GST value alongside it as the net. A standalone GST column is treated as a tax line and never enters the amount fields.