From what I've read, being an authorized user on a long established account can help a person beginning credit to develop it more quickly, but because they are not liable, it is not a great impact, more like a kickstart. I guess it's success by association. I don't know if there is any negativity if the cardholder defaults. The user still isn't liable for the debt, but does a default cancel the pros of being associated with the account? I'm not sure. Personally, in my mind it is one more issue that devalues the use of a credit report and if it has much impact on the score, again, "I know someone who pays really good" does not make a person credit worthy in their own right.
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AndyZ CRCM
My opinions are not necessarily my employers.
R+R-R=R+R
Rules and Regs minus Relationships equals Resentment and Rebellion. John Maxwell