# gateway.identity_verification.authentication_required

> For the complete machine-readable documentation index, see [llms.txt](https://apidocs.chargebee.com/llms.txt).


**gateway**

Additional authentication is required to proceed. This happens when regulatory requirements like PSD2 mandate Strong Customer Authentication (SCA), the transaction is flagged as high-risk, or the customer has not completed required identity verification steps.

## Recommended Customer Message

Additional authentication is required. Follow the provided instructions to complete the operation.

## Root Cause[](#root-cause)

-   **Strong Customer Authentication (SCA) required:** Regulatory requirements like PSD2 mandate additional authentication for certain transactions.
-   **3D Secure authentication pending:** The transaction requires the customer to complete a verification step through their bank or payment provider.
-   **High-risk transaction flagged:** The payment gateway or issuer flagged the transaction for additional security verification due to its risk profile.
-   **Incomplete identity verification:** The customer has not yet completed all required identity verification steps.

## Troubleshooting and Solutions[](#troubleshooting-and-solutions)

-   Ask the customer to follow the on-screen instructions or authentication prompts to complete the verification process.
-   For pending invoices, send a 'Pay Now' link via email and guide the customer to use it to complete 3DS and pay pending invoices.
-   If authentication fails, advise the customer to try again or contact their bank for assistance.
-   Recommend using a different payment method that does not require additional authentication, if available.
-   Ensure that your payment integration supports required authentication flows like 3D Secure.
-   Clearly inform customers in advance if additional authentication will be required for smoother transaction completion.