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Handling Underpayments and Overpayments

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Overview

When creating a temporary NGN funding account, merchants submit a principal amount. The create response returns an amount that is the exact amount the customer must transfer. The response value may be higher because the payment provider can add a collection charge. Always use the response amount as the payment instruction. Do not calculate the provider charge yourself or use the request value. This page explains what happens when a customer sends an amount that does not match the response amount.
This behavior applies only to temporary NGN funding accounts.Permanent NGN funding accounts do not enforce a specific amount and process any transfer received.

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Underpayments

If a customer sends less than the response amount, the deposit is automatically refunded to the sender’s bank account.

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Example

  • API response amount: ₦50,000
  • Customer sends: ₦45,000
  • Result: ₦45,000 is refunded to sender’s bank account
The funding account remains ACTIVE until expiry, and the customer can attempt the transfer again with the correct amount.

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Overpayments

If a customer sends more than the response amount:
  1. The correct amount is processed normally
  2. The excess amount is refunded to the sender

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Example

  • API response amount: ₦50,000
  • Customer sends: ₦55,000
  • Result:
    • ₦50,000 is processed and converted to stablecoin
    • ₦5,000 is refunded to sender’s bank account

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Fidelity Bank Exception

Fidelity Bank behaves differently:For transfers originating from Fidelity Bank, any mismatch between the response amount and the actual transfer will cause the transaction to fail entirely.
  • Underpayment from Fidelity Bank → Transaction fails
  • Overpayment from Fidelity Bank → Transaction fails
No funds are processed. The customer must initiate a new transfer with the exact response amount.

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Why This Happens

This is due to technical constraints specific to Fidelity Bank’s transfer processing system.

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Recommendation

When displaying bank details to customers, always emphasize the exact amount if there’s a possibility they are using Fidelity Bank.

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How Refunds Work

Refunds are processed automatically by Daya and typically arrive within:
  • 1-2 business days for most banks
  • May take longer depending on the sender’s bank
Merchants are not charged for refunded amounts.
Refunds are handled transparently. No merchant action is required.

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API Behavior

When an amount mismatch occurs: The deposit object reflects only the processed amount, not the refunded portion (for overpayments).

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Which Banks Are Affected?

This automatic refund behavior applies to transfers from all Nigerian banks except Fidelity Bank.

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Common Banks (Automatic Refund)

  • Access Bank
  • GTBank
  • UBA
  • Zenith Bank
  • First Bank
  • Kuda
  • Opay
  • And all others except Fidelity

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Fidelity Bank (Transaction Fails)

Exact amount match is required.

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Best Practices

When showing bank details to customers, make the create response amount highly visible and emphasize that the transfer must match it exactly. Do not substitute the request value or calculate the provider charge yourself.
If you know or suspect a customer is using Fidelity Bank, explicitly warn them that the amount must be exact.
Sandbox mirrors production behavior for amount mismatches. Test your flow with under/overpayments to see how your system handles refunds.
Set up webhook listeners for deposit.failed events to catch Fidelity Bank mismatches and notify customers to retry.

Funding Accounts

Learn about temporary NGN funding accounts

Deposit Concepts

Understand deposit lifecycle and statuses

Limits Overview

See other merchant-facing limits