How age is measured
Scoring models look at how long your accounts have been open and how long since each was used. Closed accounts in good standing can keep counting for years, which is why closing them is rarely urgent.
Building age from a thin file
Open a starter or secured card and keep it. Being added as an authorized user on a long-standing, well-managed account can also lend history. Then leave things alone — age is the one factor you cannot rush.
Protecting the age you have
Keep your oldest card open and active with a small recurring charge. Space out new accounts, since each one lowers your average age.