I've read in several places on this forum that becoming an Authorized User on someone else's credit card can affect your score (either positively or negatively depending on their account). I have been added as an AU, and their account appears on my reports. And I see alerts when their balance changes, and my score changes a few points up or down accordingly.
The confusion comes in when I read an information blip on one of myFICO's score details pages (see Score Igredients). It says "Authorized user accounts aren't considered in the calculation of this attribute." The same statement is for almost every detail there is, including Late Payments 30+ Days, Late Payments 60+ Days, Percentage of Accounts Always Paid as Agreed, Months Since Most Recent Late Payment, Revolving Utilization Percentage, Accounts with Balances, and many more.
So what's the deal? Do AU accounts affect one's score, or do they not?
