EyeOnSecure the accounts first
Change the passwords of affected accounts and, where available, turn on two-factor authentication — starting with email, because email access is the recovery route for everything else. Contact the bank or card issuer immediately if money or accounts are involved; early reports are also what limit liability under most countries' rules.
If a device was compromised, run a full security scan and consider factory-resetting it before logging back into anything. Freezing or locking cards through the banking app is usually instant and reversible, which makes it a low-cost early move.
Document while it is fresh
Keep a simple log with dates and times: what was discovered, who was contacted, reference numbers, and what was said. Screenshots of suspicious emails, texts and transactions preserve evidence that disappears quickly.
This log is not bureaucracy for its own sake — disputes with institutions, police reports and insurance claims all move faster when the timeline already exists. It also prevents the common mistake of forgetting which accounts were actually affected.
Alert the credit bureaus and report it
Contact the credit bureaus in your country, place a fraud alert or credit freeze where those tools exist, and ask what proof of the fraud they need to remove fraudulent entries. Most bureaus have dedicated fraud teams whose process is faster than a standard dispute.
File a report with the national fraud or police reporting channel, even if it feels symbolic: many institutions require a report number before they will remove fraudulent accounts, and the report starts the formal clock on your side.
What can wait until tomorrow
Day one is triage, not closure. Full credit reports from every bureau, disputes over specific fraudulent entries, replacing documents, and untangling any accounts opened in your name can follow over the next days with the log in hand.
The guides on checking whether identity has been stolen and what to do when credit was opened in your name cover the follow-up steps in detail.