Amount Tolerance

Overview

Amount Tolerance defines the acceptable variance around an Expected Amount. It is commonly used when exchange-rate conversion, decimal precision, wallet rounding, or user entry creates a small mismatch. The rule should state whether tolerance applies only below the expected amount or in both directions.

OxaPay exposes an under-paid coverage setting for invoices and white-label payments. This controls the maximum acceptable underpayment according to the merchant’s configuration. The setting should be treated as a business acceptance rule, not a correction to the on-chain amount.

Tolerance should be applied after asset, network, destination, and transaction validity have been confirmed. A payment of the right approximate value in the wrong token or to the wrong address is not acceptable. Amount comparison is only one part of Amount-Based Matching.

Overly wide tolerance can create systematic revenue leakage or be exploited by payers. Overly narrow tolerance can generate unnecessary support cases for harmless decimal differences. Merchants should test the rule against asset precision, typical order size, fee behavior, and exchange-rate movement.

The recorded payment should preserve the expected amount, Paid Amount, variance, tolerance used, and acceptance result. If policy changes later, historical payments should remain explainable under the rule active when they were evaluated.

Tolerance design should consider order value and fraud incentives. A percentage rule can allow an excessive shortfall on large invoices, while a fixed rule can be too strict for very small payments. Some systems combine a capped percentage with a fixed maximum. Testing should cover decimal truncation, exchange-rate rounding, partial transfers, fee-on-transfer tokens, and repeated attempts to exploit the boundary.