How Many Tradelines Should You Buy?

There's no magic number. The right count is the smallest one that closes the gap on your report, and you can work it out with a pen before you spend anything.

Each tradeline brings its own account age and credit limit to your file, plus the sponsor's balance, which is expected to stay at 15% or less of the limit while you're on. All of that feeds your averages, and averages don't move in a straight line.

FICO says length of credit history makes up 15% of a FICO Score. It looks at the age of your oldest account, the age of your newest account and the average age of all your accounts.

Here's how that average behaves. Say you have three accounts aged 2, 3 and 4 years. Your average is 3 years. Now add tradelines that are each 15 years old.

The first tradeline moved the average by 3 years. The second moved it 1.8, and the third 1.2. Each one still helps the arithmetic, just less than the one before it.

So the size of your file matters. On a thin file, one well-chosen account can carry a lot of the load by itself. On a file with many young accounts, a single tradeline gets diluted, and a second one does real work.

Limits stack in a similar way. Every tradeline grows your total limit, and every sponsor balance, up to 15% of that limit, joins your balances. The closer your ratio already sits to that 15% mark, the less each extra card can pull it down.

Keep scoring models in mind as well. FICO says that in recent versions of its score, authorized-user accounts have less impact than primary accounts. What you've worked out here is arithmetic on your report, not a score forecast, and results vary from file to file.

Buying more than one usually earns its keep in a few situations.

Each tradeline runs on its own schedule. It has its own purchase deadline and Reporting Period, you stay on it for two billing cycles, and then you're removed. If you're buying several for one application, choose listings whose Reporting Periods all end before that date, so every account is on your report when the lender looks. Listings come off the catalog once their purchase deadline passes, so if two specific cards fit your plan, order them together.

Each one is also covered on its own. If a tradeline doesn't post to two of the credit bureaus by the end of its Reporting Period, you choose a full refund or an exchange for another tradeline. See the guarantee for how claims work.

Spend on the gap your report shows, not on a number someone told you to hit. Run the average-age math with your own accounts, decide whether you need age, limit or both, and stop at the count that gets you there. Each one you add is another seasoned account on your report, and you're not responsible for any of the debt.

Then go get it. Open the catalog, choose the listings that close your gap with Reporting Periods that fit your timeline, and order them today.