If your name or personal information on the GMAT registration doesn't match your identification documents, it may cause issues on the test day. Here are some details on how to handle this situation:

1. Contact GMAC:
The first step is to reach out to the Graduate Management Admission Council (GMAC), the organization responsible for administering the GMAT. Contact their customer service or support team to inform them about the discrepancy in your registration information and identification documents.

2. Explain the Issue:
Clearly explain the situation to the GMAC representative. Provide details about the specific information that doesn't match, such as a misspelled name or incorrect birthdate. Be prepared to provide evidence or supporting documents to verify your identity, such as a passport, driver's license, or any other government-issued identification.

3. Request Name Change:
If the mismatch is related to your name, request a name change on your GMAT registration. GMAC may require you to submit additional documentation, such as a marriage certificate or a legal name change document, to verify the change. Follow their instructions carefully and provide all the necessary information promptly.

4. Updated Identification:
If the discrepancy is related to your identification documents, such as an expired ID or a change in address, update your identification documents before the test day. Ensure that your identification documents meet the GMAC's requirements and have not expired.

5. Confirm Changes:
Once you have made the necessary changes or updates, confirm with GMAC that the modifications have been made to your GMAT registration. Retain any confirmation emails or reference numbers provided by GMAC for future reference.

6. Bring Supporting Documents:
On the test day, bring all the necessary identification documents along with any supporting documentation related to the name change or updated information. This will help resolve any issues or discrepancies that may arise during the check-in process.

7. Arrive Early:
To allow ample time for verification and resolving any issues, arrive early at the test center. This will give you the opportunity to address any concerns and ensure a smooth check-in process.

8. Follow Test Center Instructions:
Follow all instructions provided by the test center staff regarding the verification process. Be cooperative and provide any additional documentation or information requested to verify your identity.

Conclusion:
It is crucial to ensure that your name and personal information on the GMAT registration match your identification documents. In case of any discrepancies, promptly contact GMAC, follow their instructions, and provide the necessary supporting documents. Arriving early on the test day and cooperating with the test center staff will help resolve any issues and ensure a smooth testing experience.