CheckoutCheckout Overview

Fee pass-through

Why passing a card fee to your customer costs slightly more than the headline rate

Card fees are charged on the total amount the customer pays, not on your product price. When you pass a fee to the customer, the fee gets charged on itself — so a “3% fee” always ends up costing a little more than 3%.

The one rule to remember

Fees are charged on the total amount of the purchase, not the subtotal/settlement amount.

A simple example

You sell a $10 sandwich and want the customer to cover a 3% card fee.

What most people expect

Sandwich: $10.00

Add 3%: $0.30

Customer pays: $10.30

You keep: $10.00

What actually happens

The network charges 3% on the full $10.30.

Fee = 3% × $10.30 = $0.31

You keep = $10.30 − $0.31 = $9.99

You added exactly 3%, but still came up short — because the fee applied to the fee.

To actually net your full price

Charge $10 ÷ (1 − 0.03) = $10.31. The 3% fee on $10.31 is $0.31, leaving you exactly $10.00.

This isn’t a Coinflow quirk. Every payment system works this way — Visa interchange, chargeback protection, all of it applies to the full transaction amount. Chargeback protection in particular insures the entire purchase, so its variable fee applies to the entire amount too.

The math

Subtotal
amount

Your product price — what you want to keep.

Total
amount

What the customer actually pays.

Variable
decimal

The percentage fee as a decimal (e.g. 0.045 = 4.5%).

Fixed
amount

The flat per-transaction fee.

Because the variable fee applies to the Total, the relationship is:

The fee applies to the total, not the subtotal
Total = Variable × Total + Subtotal + Fixed

Note that Variable is multiplied by Total, not by Subtotal. That’s the whole point. Solving for Total:

Solving for the total
Total = (Subtotal + Fixed) / (1 − Variable)
Example — Subtotal $100, Variable 0.045, Fixed $0.45
Total = ($100 + $0.45) / (1 − 0.045)
Total = $100.45 / 0.955
Total = $105.18

The customer pays $105.18 — that’s 5.18% on top of the $100 subtotal, not 4.5%, because the 4.5% applies to the full total and there’s a fixed fee on top.

Three ways to handle fees

Under the hood, every fee dimension — the credit card processing fee, chargeback protection fee, gas fee, FX fee, and network fee — is independently configurable per payment method via a setting Coinflow calls a fee payer mode. It has three possible values: user, merchant, and invoice.

Fee payer mode: user

The customer is charged the product price plus all fees. The full amount hits their card, the processor deducts the fees, and you receive your full product price. This is the case the math above covers, and it’s the default for every fee dimension on every payment method unless your account has been configured otherwise.

Don't confuse this with invoiced payout fees

If you cover withdrawal/payout processing fees on behalf of your customers, those are also billed via a monthly invoice — but that’s a separate withdrawal-fee setting, not the pay-in fee payer mode described here. See Add Your Own Payout Fees for that flow.