When you're dealing with payment processing, few errors are as frustrating as one that seems to contradict basic math: "scn_amount_too_small". It’s Stripe's way of politely telling your MuleSoft application that the amount you're trying to charge, even if it looks reasonable to you, falls below their minimum processing threshold for that specific currency.

This is a particularly common headache in NetSuite integrations, where line items can sometimes result in very small calculated values or partial payments. Let's break down why this happens and how to fix it within your MuleSoft flows.

The "Quick Fix" for the Impatient

The "scn_amount_too_small" error almost always means the calculated amount sent to Stripe, in its smallest currency unit, is less than Stripe's minimum allowed charge for that currency. Double-check your DataWeave transformation to ensure that NetSuite's amount field is correctly multiplied by 100 for zero-decimal currencies (like JPY) or if an unintended rounding error is occurring before it hits Stripe.

Understanding Stripe's Minimum Charge Amounts

Stripe, like most payment processors, has minimum amounts it will process. This isn't just arbitrary; it's to cover transaction fees and prevent abuse. These minimums vary by currency:

USD, EUR, GBP, CAD, AUD: Typically 50 cents (e.g., $0.50, €0.50). This translates to 50 in Stripe's smallest unit (e.g., amount: 50 for USD means $0.50).

JPY (Japanese Yen): Typically 100 yen. Since JPY is a zero-decimal currency, this translates to 100 in Stripe's amount field.

Other currencies have their own specific minimums.

If your MuleSoft flow tries to send amount: 1 (which Stripe interprets as $0.01) for a USD transaction, you'll hit this error.

Real-World Scenario: The NetSuite Micro-Adjustment

Consider a scenario: A NetSuite invoice has a base amount of $100, but due to a loyalty discount applied after initial calculation, the final amount due becomes $0.25. When your MuleSoft flow extracts this $0.25 and sends it to Stripe, the "scn_amount_too_small" error will fire because $0.25 is below the $0.50 minimum for USD.

Another common case is partial refunds or re-authorizations where the remaining balance is tiny.

Step-by-Step Resolution in MuleSoft

1. Verify Your DataWeave Transformation (The Usual Suspect)

This is where most "scn_amount_too_small" errors originate. Stripe expects amounts in their smallest currency unit (e.g., cents for USD, yen for JPY). NetSuite typically provides amounts in the standard decimal format (e.g., 25.50 for $25.50).

The Problem: If your DataWeave isn't multiplying decimal amounts by 100 (for two-decimal currencies) or handling zero-decimal currencies correctly, you're sending $0.25 as amount: 0.25 (which Stripe sees as less than a penny).

The Fix: Ensure your DataWeave correctly transforms the amount field.

%dw 2.0
output application/json
---
{
  "amount": (payload.netsuiteAmount * 100) as Number, // For USD, EUR, etc.
  "currency": payload.currency
  // ... other Stripe fields
}

For zero-decimal currencies (like JPY):

%dw 2.0
output application/json
---
{
  "amount": payload.netsuiteAmount as Number, // No * 100 needed
  "currency": payload.currency
  // ... other Stripe fields
}

Note : Double-check the as Number coercion, as sometimes string values can cause issues.

2.Implement a Minimum Amount Check in MuleSoft

Before even calling the Stripe connector, add a validation step in your MuleSoft flow.

The Fix: Use a Choice router or Filter component to check the calculated amount. If it falls below Stripe's minimum, you can:

Log an error and skip the Stripe call.

Route it to a manual review process in NetSuite.

Consolidate the charge with a future transaction (if business logic allows).


<choice doc:name="Check Minimum Amount">
    <when expression="#[payload.amount <= 50 and payload.currency == 'usd']">
        <logger message="Amount #[payload.amount] for USD is too small." level="WARN" />
        <raise-error type="APP:AMOUNT_TOO_SMALL" description="Stripe minimum charge not met." />
    </when>
    <otherwise>
        <stripe:create-charge config-ref="Stripe_Config" ... />
    </otherwise>
</choice>

Confirm NetSuite's Currency Configuration

Ensure the currency field being extracted from NetSuite is accurate and consistent with what Stripe expects.

The Problem: If NetSuite's currency field is accidentally missing or malformed, Stripe might default to a currency with an unexpected minimum.
The Fix: Always explicitly pass the currency parameter to Stripe, derived directly from your NetSuite transaction data.

4. Review NetSuite Rounding Rules

NetSuite has its own internal rounding rules for taxes, discounts, and totals. These can sometimes result in amounts that, when extracted and re-calculated in MuleSoft, dip below Stripe's minimums.

The Fix: Understand how NetSuite rounds final transaction amounts, especially for complex invoices. Consider if your MuleSoft flow needs to do its own rounding up to the nearest Stripe minimum if the amount is marginal.

The Final Word

The "scn_amount_too_small" error is a signal that your MuleSoft flow and NetSuite data need a careful review, primarily around how amounts are formatted and validated before they hit Stripe. By implementing robust DataWeave transformations and pre-validation checks, you can ensure your transactions big or small are handled correctly.

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