Buyers ask about American Express tradelines all the time, usually because they’ve seen an Amex card on a listing with 20 years of history and assume that’s a huge score boost. It can be. But there’s a specific quirk in how Amex reports authorized users that changes the math entirely — and most buyers don’t know about it until they’ve already paid. Related reading: amex authorized user — covers the mechanics in more detail. Also: credit piggybacking — the broader context for how authorized user tradelines work.





