Understanding your Mainstreet Credit Union data breach notification letter
If a Mainstreet Credit Union letter arrived in your mailbox, here is what it means, why you received it, and the free steps you can take right now.
Why you received this letter
Mainstreet Credit Union is a financial institution that provides banking services, including personal savings, checking accounts, and loan products to its members. As a financial entity, the credit union maintains sensitive personal and financial records necessary for account management, credit reporting, and regulatory compliance. In 2026, the company officially reported a data security incident to the Indiana Attorney General, confirming that unauthorized access to their systems occurred. If you received a data breach notification letter from Mainstreet Credit Union, it indicates that your personal information held within their systems may have been compromised. This notice is intended to inform you of the incident and provide guidance on the steps you should take to protect your financial identity and monitor your accounts for suspicious activity.
What to do after the letter
Confirm the notice is genuine
A legitimate Mainstreet Credit Union notice references the specific incident reported to the Indiana Attorney General and describes which categories of your information were involved. Compare the letter against the public filing before acting on any links or phone numbers it contains.
Keep the letter — it is your proof of connection
The notification letter is the document that ties your personal information to this incident. Keep the original and photograph it. If you later request a case review, this letter is the strongest evidence that you were among the affected individuals.
Protect your accounts and credit
Depending on what was exposed, consider a free credit freeze with all three bureaus, new passwords for reused credentials, and monitoring of financial statements. These steps are free and do not require you to wait for anyone's permission.
Find out whether you have a claim
Whether the Mainstreet Credit Union breach gives you a legal claim depends on the facts. A free, no-obligation case review will tell you where you stand — there is no cost and no commitment to find out.
This page summarizes a data breach reported to the Indiana Attorney General for informational purposes and is attorney advertising. It does not create an attorney-client relationship. DataBreachLegalCenter.com does not provide legal advice through this page.