What immediate action should Jack take if he believes his identity was stolen?

Putting a credit freeze on all three credit files is the most effective immediate action Jack can take if he believes his identity has been stolen. A credit freeze restricts access to his credit report, which means that creditors cannot pull his credit, making it more difficult for identity thieves to open accounts in his name. This is a critical step in preventing further fraudulent activities.

While notifying the police is important for documenting the theft and potentially aiding in recovering damages, it does not provide immediate protection against further misuse of his identity. Changing passwords and canceling credit cards can be prudent steps, but they may not directly stop new credit accounts from being opened in his name. A credit freeze acts as a solid barrier to new credit applications and is designed specifically to protect individuals from the ramifications of identity theft.