Most people think they understand their credit card. They know the limit, the interest rate, maybe the rewards rate if they’ve been paying attention. But there’s a whole layer underneath that — issuer quirks, authorized user mechanics, utilization timing — that most cardholders never learn about until something bites them. I found out some of this the hard way. Here are 7 things you probably didn’t know about credit cards that are actually worth knowing.
[Related: buy tradelines from us or read the “Resources” section below]
1. You can legally pay to be added as an authorized user
This is probably the most underused credit-building strategy out there. When you become an authorized user on someone’s credit card, their account history — the age, the limit, the payment record, the utilization — can post to your credit report. If the account has good stats, it can have a real effect on your score.
The part most people don’t know: you can buy this access from strangers. It’s called an authorized user tradeline, and there are entire brokers (Tradeline Supply Company is the biggest) who facilitate these transactions. The seller adds you for a couple of months, the account posts to your report, and then you’re removed. There are a lot of common questions about how the process works — it’s not shady, it’s been around for decades, and the major credit bureaus are aware of it.
Related: credit card hacks — worth reading if this applies to you. Related: what happens if you go over your credit limit once — worth reading if this applies to you.
If you want a Chase tradeline specifically, mine is listed here — $37K limit, opened in 2020.
2. The issuer name on the card doesn’t matter for your score
People ask me all the time whether a Chase tradeline is better than a Capital One tradeline. The answer is: for your credit score, it doesn’t matter at all. The FICO scoring model looks at the account’s limit, age, utilization, and payment history — not whether the card has a Chase logo or a Capital One logo on it.
Where it might matter is in lender underwriting. Some mortgage lenders have overlays that treat different issuers differently, or care about the mix of accounts. But for the score itself, a $30,000 Capital One card opened years ago is identical to a $30,000 Chase card opened at the same time. Chase tradelines do sell faster on the market because buyers assume they’re better — which is why I try to add the Capital One ones first.
3. Amex authorized users get a different account open date than you’d expect
This one catches people off guard. If you’re added as an authorized user to a 20-year-old American Express card, you might assume that long history is going to post to your report with the original open date. It doesn’t. Since around 2015, Amex reports the authorized user’s account open date as the date they were added — not the card’s original date. So a 20-year-old Amex card looks like a brand new account on your report if you were just added.
This is why Amex tradelines are much less valuable as a credit-building tool despite the brand prestige. It’s counterintuitive, and it’s one of those things nobody tells you until you’ve already paid for one and wondered why the boost was smaller than expected.
4. Bank of America can close your accounts without much warning
This one I know personally. Bank of America has a reputation for closing cards if they suspect unusual authorized user activity — and “unusual” is their call to make. They don’t necessarily call you. They just close it.
I had a $40,000 Bank of America card closed on me. It was one of my better cards by limit, and losing it was a real setback for what I was building. (The lesson: don’t keep your most important cards at BoA if you’re doing any kind of AU activity, even legitimate selling.) Other issuers have been much more stable in my experience — Capital One, US Bank, Fidelity are all cards I’d consider seller-friendly.
5. Your utilization is snapshot-based, not average-based
Credit utilization is calculated based on the balances reported on your statement date, not some rolling average. That means if your statement closes on the 15th with a $4,000 balance on a $5,000 card, you’re reporting 80% utilization — even if you pay it off in full on the 16th.
This matters for people who use credit cards heavily for rewards but always pay on time. They’re often confused about why their score isn’t higher. The answer is timing. If you want low reported utilization, pay down the card before the statement closes, not after. The CFPB’s overview of credit score factors explains the basics well if you want the official breakdown.
6. Citi has a known problem with authorized user posting
If you buy an authorized user tradeline, you want it to actually post to your credit report. Most issuers do this reliably. Citi is the notable exception — they’re notorious in the tradeline industry for inconsistent authorized user posting. Some buyers get the post, some don’t, and there’s no great predictor of which way it goes.
This is another thing nobody mentions in general credit card articles. If you’re specifically trying to use authorized user tradelines to build credit, avoid Citi-issued cards. The risk of the post not showing up is real enough that most reputable sellers won’t list them.
7. Opening new cards to build credit can temporarily hurt your score
People who want to build credit sometimes open multiple cards at once, figuring more accounts means a better credit mix. The problem: each new application generates a hard inquiry, and hard inquiries drag your score down in the short term. Multiple inquiries in a short window can make you look like a credit risk, even if each individual card is perfectly fine.
I’ve had as many as 10 hard inquiries on my report at one point — not my proudest stretch. Getting back down to around 5 took time and deliberate restraint. If you need to build credit history quickly without hitting your score with hard inquiries, becoming an authorized user is a much cleaner path. You get the account history benefit without any inquiry at all. If you’re looking for options, browse the tradelines I have for sale.
Resources
The following is a list of resources to start learning about how credit scores are calculated. We have a list of tradelines for sale, and a tradelines FAQ. Also various posts about tradelines, and a chart of tradeline prices from competitor sites. Finally, a contact form to ask further questions.
Please feel welcome to ask any questions below.
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