Discounted services: avoid subtracting the same discount twice

Distinguish list amount, discount and final item amount

Inspect a known discounted transaction in the original source. Identify the item’s list amount, the discount amount or percentage, the final sale amount and any tax component. Do not assume that a column labelled “Sales” is before discount or that a discount column still needs to be subtracted.

Keep those source columns in the review record even if only the final item amount is used for calculation. They explain how the accepted basis was formed and make it possible to investigate a source-reported commission calculated on a different assumption.

Make the two possible bases visible

In this fictional AUD example, the supplied exclusive list basis is $200.00. A 20% discount reduces it by $40.00 to $160.00. The supplied commission rate is 40%. The table compares two assumptions; it does not decide which one applies to a real arrangement.

Detect a discount applied twice

Suppose the export already supplies the $160.00 exclusive final basis but the worksheet subtracts the $40.00 discount again. It calculates $120.00 × 40% = $48.00. The intended after-discount example was $64.00, so the repeated subtraction creates a $16.00 understatement.

Check one discounted and one undiscounted transaction when mapping a new file. A mapping can appear correct on full-price sales while failing on discounted ones. Do not compensate by raising the commission rate: the error belongs to the amount definition, not the percentage.

Keep basket discounts and stacked percentages explicit

A discount applied to an entire basket may need an item allocation before service and retail rates can be calculated separately. Use the source allocation when available. If it is absent, obtain a recorded allocation method rather than placing the full discount against each item or arbitrarily assigning it to one staff member.

Sequential percentages also need care. On a $200.00 basis, a 20% discount followed by a further 10% discount gives $200.00 × 0.80 × 0.90 = $144.00, an effective 28% reduction. Adding the percentages to get 30% would produce $140.00. At 40% commission those outcomes differ by $1.60.

Use a source-led discount check

Retain the actual source values rather than reconstructing a list price from a rounded discount percentage when the original values are available. Rounded percentage displays can conceal the precise amount applied by the source transaction.

1. Identify the original item and its list amount, discount and final amount.
2. Confirm whether the chosen commission basis is before or after the discount.
3. Check whether tax values refer to the final discounted sale.
4. Verify any item allocation for a basket-level discount.
5. Recalculate the line and compare it with the source-reported commission.
6. Record the agreed amount definition and any explained difference.

Use the tool for comparison and the source for evidence

Trimsum calculates flat commission from the mapped signed item amount and selected tax basis. It does not infer whether a separate discount should be added back, allocate a basket discount or enforce an employment arrangement. Prepare a source that matches the intended calculation rather than silently altering the import.

The discount-impact tool can show the difference between supplied list and discounted bases. Use that result to explain a review question, then keep the confirmed basis and source references with the recurring close. The amount of a discount alone does not establish who should bear its commission effect.