How you change your last name online through service Canada website

The change online is to confirm your documents will be changed though your health card and drivers license will be updated separately. Your sin card will remain the same only thing the system does is change your name on it. The famiy surname and current is what your changing to your husbands. Photocopy the marriage license as they would need a proof of that for their records as it would be noted on the form.

My husband went through all this himself to change his last name to mine and they did it as described as above. It did take time though it was done. Also consider your passport for the same process of proof to give the office when changing your last name.

Are you just assuming your spouse's name or do you want it changed legally (ie your birth certificate?) If it's just assuming your spouse's last name, you need to go to Service Ontario in person with your marriage certificate and they'll mail you the updated cards.

https://www.ontario.ca/page/change-your-last-name#section-0

You only need to change the SIN if you are legally changing your name.