GST is treated as pass-through — collected from the buyer and offset by input credit on your purchase, so it is not counted as a cost. Fees are charged on the gross selling price.
How this SKU profit calculation works
For each unit sold, your net revenue is the selling price with GST stripped out (GST is money you collect for the government, not income). From that we subtract the four real costs that eat your margin:
- Purchase cost — what you pay your supplier for the unit.
- Courier / shipping — the per-order delivery cost you bear.
- Marketplace & payment fees — commission and gateway charges, taken on the gross selling price.
- Return allowance — returns cost you reverse logistics and often non-refundable fees; we spread that across every unit using your return rate.
What's left is your true profit per SKU — the number that tells you whether a product actually makes money once every cost is counted.