Your credit score—three numbers that range somewhere between a low of 300 and high of 850—count for a lot more than just whether you'll qualify for the plastic card the cashier at your local department store offers you. The digits signifying your perceived creditworthiness from agencies Experian, Equifax and TransUnion play a role in many of life's major transactional decisions, from love and living quarters to employment and security. Here's a look at eight areas, some surprising, where a less-than-stellar credit score—anything under 720, according to CreditKarma.com—can impact how you'll pay, or whether you get to "play" at all.

—By CNBC's Kenneth Kiesnoski
Posted 25 February 2015

You're in the army (or CIA or FBI) now ... or maybe not, if you've got bad credit. You may be denied the all-important security clearance required for certain government and defense-related jobs. To quote Guideline F of the State Department's Adjudicative Guidelines for Determining Eligibility for Access to Classified Information, "Failure or inability to live within one's means, satisfy debts, and meet financial obligations may indicate poor self-control, lack of judgment, or unwillingness to abide by rules and regulations, all of which can raise questions about an individual's reliability, trustworthiness and ability to protect classified information." In other words, if you're broke, you may be tempted to engage in unethical behavior—such as betraying your country for monetary gain.

Bad credit isn't sexy. A 2013 poll of singles by FreeCreditScore.com found that 57 percent of men and 75 percent of women take creditworthiness into consideration before saying "yes" to dinner and drinks. And when it comes to potential marriages, a fifth of men and nearly a third of women say they wouldn't get hitched to someone saddled with a shabby credit report. They have good reason: While the act of tying the knot won't merge a couple's individual credit reports or lower one or the other's individual scores, one spouse's negative credit profile will, in fact, impact a couple's success in opening joint financial accounts or applying for products such as home mortgages.

Many prospective employers now ask for permission to access your credit report as part of your application process. This is a hazy area of both jurisprudence and hiring practice. Technically, the credit bureaus do not and cannot (legally) share your actual credit score with your current or future boss. If you give permission, employers can, however, see an amended version of your credit report—depending on where your reside. At last count, 10 states have taken action to outlaw or restrict employer access to such information, according to the National Conference of State Legislatures.

Moving in with that new mate? Or still single but looking for new digs? You may have trouble renting a new apartment or home if you have a tarnished credit report. It's become commonplace for landlords, or the real estate brokers they employ, to run a credit check before handing over the keys to your new flat. And if they do rent to you despite your low score, you may have to fork over a hefty security deposit before moving day.

So you've got your new job and apartment. Now you need lights, gas and Internet service. Guess what? As the Federal Trade Commission puts it, "Applying for utility services is applying for credit." Utility companies, such as cable TV providers and power companies, run credit checks before setting up new accounts and turning on services. If your credit isn't in tiptop shape, you might very well have to pony up a hefty, or heftier, security deposit—or, in worst-case scenarios, be denied services.

Once you've rented an apartment, bought a car or maybe even gotten engaged, you likely will want to insure against damage and injury to pricey new possessions—not to mention your loved ones—but a poor credit score can get in the way. Insurers use credit scores to predict how likely a consumer will pay late on his or her premium, as well as make insurance claims. That's because some research has suggested a correlation between low credit scores and high-risk behavior.

Okay, this is a more obvious one. If you're ready to take the big leap and buy a home, your credit rating is all-important. Want the absolute lowest interest rate and have that "good" 720 score? Forget it; you'll need a rating of 760 or better to qualify for the latest rates, many now at historical lows. To illustrate: At the top end of the credit score scale, borrowers pay a 3.285 percent rate, but those with scores between 680 and 699 are subject to 3.684 percent, according to myFICO.com.

Another no-brainer. If you apply for a new credit account, the card issuer will use your credit score information to determine not only your eligibility and interest rate but also whether you enjoy perks such as rewards points and annual fee waivers. And that existing account? Remember that your current credit card company is keeping tabs on your score and may decide to change the terms of your account—including lowering your available credit limit—should that score take a dip.