I asked people to add me to their credit cards, and all the information for the specific accounts were reported on my credit report. When I checked my credit score a few years ago, it was in the 400s. about a year or 2 ago, I asked people to add me to their good accounts and my credit score raised to 600s. I even got approved for my own credit cards!
You will not get your mom's credit, just the information for the specific account since it was opened. And using some mystic formula that no one knows, your score will be calculated. Also creditors will know that you are merely the authorized user, but is should still help your credit rating.
One way of building your account is to get a savings secured loan, which is great because the account will be in your name. I have one of those accounts and it is great. This is why:
The loan is for $600, so they put a hold on $600 of my savings. However, everytime I pay on the loan, they remove the hold for the amount I paid. So, when I pay $50, they reduce the hold from $600 to $550. Basically, you dont have to wait for the entire period of the loan to get back your money! Therefore, you can use the same $50 to make the payments each month!
A secured load is a great way to improve your credit over time. If you have any charge off, you should take care of that.
