My wife is an AU on 7 of my credit cards, when I pull her FICO 8 score from the free Discover Fico 8 website, her EX score and report ONLY lists those credit cards that she applied to under her name. This is with UTIL, total accounts and AAoA. However, her Vantage 3.0 score from CK is much higher (like 60+ points) and lists all of the AU accounts. So using a Vantage 3 model her AAoA is 7.6 years, using the FICO 8 model from EX, her AAoA is 1 year.
I was listed on one of my wife's cards, it showed up on CK and Vantage 3, I asked chase to remove me, my Vantage score went up a lot. It didn't appear to affect my FICO 8 score, though at the time I wasn't really watching it, I was just keeping track of is on a database and NOT pulling any sort of summery report.
What is interesting, although my wife's FICO 8 score was 670 Vs my 800, she gets a lot more credit offers that I do, and the last card she applied to was an AMEX BCP card with a $15K liimit, a higher limit to start with than I ever got. Her second card was a BOA card rewards card with only a $1.K CL. I am sure she was offered the BOA card because she had her own checking account at BOA.
So while I am sure at least for us, FICO 8 does not include AU accounts, it is quite possible that the AU accounts do have an effect on how credit card companies evaluate whether to accept,offer or deny credit.
BTW, the best way I have seen to get credit cards and thus a good credit file for someone without a credit history is to open a checking account in their name, use direct deposit, get a bonus of $200-$300 for signing up, and then the bank will offer their credit cards to the checking account holder. I iinclude direct deposit because that is the easiest way to get a no fee checking acoount. BUT after some time, all you need to do to keep the checking account no fee varies, either a min balance of $1600 for some banks or you have checking and credit cards with No min balance for other bansk. Like US Bank is NO min balance on checking as long as you have credit lines and a checking acount at the same bank.
The absolutely best way to start a good credit file is to get your wife signed up as a joint holder on an older tradeline, but I don't think that is easy, and posters say one of the companies that do that is Discover, though I have not asked for my wife to be a joint holder, so I don't know how hard that would be.
FWIW, the EX report on my mothers credit history list's my wife as a joint holder on my mother's Discover, though that is NOt correct information, she is accually an AU. Discover the company list my wife an an AU, no idea why EX lists her as joint. No idea what my wifes detailed credit report says as I have yet to get a copy, just summaries like you get from the free discover website.
