Percentage Fees: Identify the Charged Amount

A percentage fee is incomplete information until its base is known. A seller can correctly multiply a stated percentage and still underestimate the deduction by applying it only to merchandise. Build a fee map with one row for every charge: the rate, the amount subject to that rate, any fixed charge, and the document that defines the calculation. Different charges on the same order do not necessarily share a base.

One order, two fee bases

Consider a hypothetical order with $80 of merchandise after discounts and a $10 delivery charge. This example excludes taxes. A hypothetical marketplace fee of 8% applies to the $80 merchandise amount, while a hypothetical payment fee of 3% applies to the full $90 customer payment. The deductions are $6.40 and $2.70, totaling $9.10. Applying both percentages to merchandise would produce $8.80 and miss $0.30 on this one order.

Why percentages cannot always be added

Adding 8% and 3% gives 11%, but multiplying that by either $80 or $90 does not reproduce $9.10. You may combine rates only when they apply to the same base and have compatible rules. The effective fee rate here is $9.10 divided by $90, or 10.11% of customer payments. Relative to merchandise revenue it is 11.375%. Both ratios are valid measurements, but they answer different questions and must carry their denominator labels.

Build the order reconciliation

Export a small sample of settled orders and match each deduction to the underlying order identifier. Include an ordinary order, a discounted order, a partially refunded order, and one with a separate shipping charge. Check whether the percentage is assessed before or after the discount and whether fee reversals follow refunds. Keep collected amounts held for third parties separate from revenue even if an agreement includes them in a fee base.

Turn the map into a pricing input

Suppose product cost is $42 and delivery actually costs $12. Contribution before other variable expenses is $90 minus $42 minus $12 minus $9.10, or $26.90. It is not the $80 merchandise price minus product cost alone. If the delivery charge changes, only the fee rows whose bases include delivery should change. This distinction becomes useful when comparing a higher merchandise price with a separate delivery charge.

Limits and checks

The percentages above are invented for arithmetic and describe no current platform. Obtain the supported fee rules for the exact account, country, product, and payment method before replacing them. Minimum fees, tiered amounts, currency conversion, or tax on a service fee can require separate rows. Do not infer rules from one rounded payout. Reconcile several transactions and retain full precision until the final currency amount, then investigate differences rather than assigning them to profit.

Method references: Stripe: balance transaction types. Accessed October 22, 2026. All dollar figures are hypothetical worked examples.