Having no credit history is a different problem from having a poor one, and it fails differently. The Consumer Financial Protection Bureau's 2015 report Data Point: Credit Invisibles separates two groups. Credit invisible consumers have no credit record at any of the three nationwide agencies at all. Unscorable consumers have a record that a scoring model cannot produce a number from, either because it contains too little information, meaning too few accounts or accounts too new to carry much payment history, or because it has gone stale, meaning it holds no recently reported activity.
As of 2010, the Bureau estimated that 26 million consumers, about 11% of the adult population, were credit invisible, and that a further 19 million, or 8.3%, had records treated as unscorable by a commercially available scoring model. Those unscorable records split almost evenly between the two causes: 9.9 million for insufficient history and 9.6 million for a lack of recent activity. The Bureau also found the pattern is strongly related to income, with almost 30% of consumers in low-income neighborhoods credit invisible and another 15% unscored, against roughly 4% and 5% in upper-income neighborhoods. The Bureau is explicit that what counts as "insufficient" or "stale" is proprietary to each model and differs between them, so there is no threshold to quote.
The practical consequence is the part worth carrying. A low score is a bad answer; no score is no answer, and lenders respond to the two differently. An application that cannot be scored may be declined outright, routed to manual underwriting, priced from other information, or approved only with a cosigner. And because staleness is one of the two routes, a household can arrive at unscorable by paying everything off and then borrowing nothing for years, which is the case nobody warns about and which affects retirees and debt-averse households in particular.
A thin history is often somebody else's decision, not yours. Nothing in the Fair Credit Reporting Act requires a creditor to report anything. What 15 USC 1681s-2(a)(1)(A) does is prohibit furnishing information the furnisher knows or has reasonable cause to believe is inaccurate. Furnishing itself is voluntary, so years of on-time payments to a creditor that does not report to the nationwide agencies leave no trace in your history at all. That is why the question "does this account report, and to which agencies" is worth asking before opening something specifically to build a record.
Regulation B addresses credit history directly, and it gives an applicant two rights that are almost never exercised. 12 CFR 1002.6(b)(6) provides that to the extent a creditor considers credit history at all, it shall consider three things. First, the history of accounts designated as accounts the applicant and the applicant's spouse are permitted to use or are both contractually liable on, which is why the designation mechanism below is the step that makes this limb bite. Second, on the applicant's request, any information the applicant presents tending to indicate that the history being considered does not accurately reflect their creditworthiness. Third, on the applicant's request, the history of any account reported in the name of a spouse or former spouse that the applicant can demonstrate accurately reflects their creditworthiness.
The second of those is the route for someone whose file misrepresents them, and it is a request rather than something a creditor will offer. The third is the route for someone whose borrowing life was recorded under another person's name, which is a common position after a divorce or the death of a spouse.
There is also a mechanism for getting a shared account onto your own file. 12 CFR 1002.10 requires a creditor that furnishes credit information to designate any new account to reflect the participation of both spouses where one is permitted to use it or is contractually liable, and to designate an existing account that way within 90 days of receiving a written request from either spouse. Once designated, the creditor must furnish the information in a manner that lets the agency provide access under each spouse's name. So a long-standing household account can be made to count for both people, and the trigger is a written request with a deadline attached to it.
Building a history is a question of which accounts report, not of how responsibly you behave. The routes that create a record are ones a nationwide agency receives data about: a secured card, a credit-builder loan, being added as an authorized user, a cosigned or jointly liable account, and the spousal designation above. Rent and utility payment histories can also reach some agencies through some landlords and third-party services, though the coverage is uneven and worth confirming rather than assuming. What none of these do is work quickly: a record accumulates by elapsed time as well as by conduct, so the useful move is opening the thinnest acceptable account early and leaving it open rather than opening several later.