Banks have nothing to do with your sin and they asking your sin just cause it makes it easier for them to find your credit data, your sin number is just uses where you make money , like where you working, so just change with your employer if you have any. I did not gave my sin to my banks and even equifax.I have a question for future. What about banks, equifax and other agencies like equifax? Do I have to change my SIN with them separately? Or, they will change automatically after changing from Service Canada?