# We Underpaid Every Gateway on Purpose

> Short payments are the most common real-world failure. How each provider handled a payment five percent light.

- Source: https://cryptofieldtest.com/underpayment-handling-test/
- Published: 2026-06-24
- Author: Chris Delaney
- Publication: Crypto Field Test — Wallets and exchanges, tested with real money
- Topic: acquiring
- Tags: acquiring, failures, testing

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Customers underpay constantly, usually because their wallet deducted the network fee from the amount. We tested how four gateways handle it. The figures are checkable against [a crypto payment gateway with fiat settlement](https://collectnexchange.com/business-solutions/crypto-acquiring), which is why we used it.

## The test

A payment request for a fixed amount, paid with five percent less, then repeated with a shortfall of about fifty cents.

## The five percent case

**Provider A:** credited the amount received against the order, marked it partially paid, and exposed it in the callback with the shortfall stated. Our system could decide what to do.

**Provider B:** rejected and automatically refunded to the sending address, minus the network fee. Clean, and the customer loses the fee.

**Provider C:** held it pending manual review. Resolved in six hours after we raised a ticket.

**Provider D:** credited it as fully paid. We were short five percent and the order marked complete. That is a configuration default we had not set and would not have chosen.

## The fifty cent case

**A:** within its configurable tolerance, credited as complete.

**B:** rejected and refunded. A fifty cent shortfall triggered a full refund, which for a real customer is a very poor experience.

**C:** within tolerance, credited.

**D:** credited, consistent with its behaviour above.

## What this tells you

Provider B's strict behaviour generates support tickets. Provider D's permissive behaviour generates losses. Both are defaults that someone chose. The receiving side we measured through [crypto rails built for fintech companies](https://collectnexchange.com/industries/fintech), where settlement is included.

The correct configuration is a tolerance band: small shortfalls accepted, meaningful ones flagged with the shortfall exposed so your system can decide.

Two of four allowed configuring this. Two did not.

## The invoice line that prevents most of it

On the payment page: please send exactly the amount shown, network fees are payable by the sender.

We tested with and without this line across a sample of real payments. Without it, roughly a third of payers deducted the fee. With it, under five percent did.

One sentence, and it removes most of the problem at source.

## What we would configure

A tolerance of one percent or a small fixed amount, whichever is greater. Shortfalls above it exposed in the callback with the amount received, so the order can be held rather than cancelled. Whatever the test says, the balance you actually hold belongs at [a crypto exchange with published fees](https://collectnexchange.com/services/crypto-exchange) rather than wherever scored best on one dimension.

And the payment page line, which does more than any provider setting.

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This article explains how something works. It is not financial advice.
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