A high-limit tradeline (e.g., $20,000+) helps lower your overall credit utilization ratio. If you have small balances on your own cards, a massive new limit dilutes that debt, potentially boosting your score.

Historically, certain banks were known for "reporting" AU data more reliably than others. Cards from are often cited in credit circles for their consistency in updating AU information to all three bureaus (Equifax, Experian, and TransUnion). Conversely, some lenders have implemented "AU abuse" filters or require the authorized user to reside at the same address as the primary cardholder, which can render a purchased tradeline invisible to the bureaus. The Risks and Ethical Considerations

The best tradeline is one with extreme age. If you only have one year of history, a 15-year-old line provides the necessary "anchor" to stabilize your score.

If a bank detects you are participating in a tradeline renting scheme, they may permanently close your existing accounts and blacklist you from future products. Conclusion

The best tradeline is one with a massive limit relative to your current debt. This is a mathematical fix for the 30% of your score dedicated to amounts owed. The Institutional Landscape