How old do you have to be to get a credit card?

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Building credit as soon as possible is often hailed as a pivotal step in establishing a strong financial standing. There are different ways to go about building credit, and opening a credit card is one of the most popular.

But if you're looking to open a credit card, you'll want to understand the age requirements and any other qualifications you need to meet.

Below, CNBC Select reviews the requirements for getting a credit card and some of our favorite picks for new cards.

The minimum age to open a credit card as the primary account holder is 18. But due to regulations from the Credit CARD Act of 2009, applicants 18 to 20 might encounter stricter verification requirements, including showing proof that they can independently repay what they borrow. Having income — such as a salary, regular paychecks, commission checks, or income from investments — protects young consumers from taking on more debt than they can handle.

Once you turn 21, you won't be bound by these rules, though card issuers still review your income and it remains important to answer all application questions honestly.

Here's how Discover identifies what it counts as "total gross income," according to the description on the Discover it® chrome application:

"Income means wages, salary or tips, you currently earn or can reasonably expect to earn. Other examples include bonus pay, commissions, and income from rental property, interest, dividends and retirement benefits paid.

You do not have to include alimony, child support or separate maintenance income unless you want it considered as a basis for repayment.

If you are 21 or older, you may include another person's income that is available to you. If you are under 21, you may consider the amount of another person's income that is regularly deposited into your account."

If you meet the requirements for opening a credit card as the primary account holder, check out some of CNBC Select's best credit cards for beginners, students and cash back.

Information about the Discover cards has been collected independently by CNBC and has not been reviewed or provided by the issuer of the card prior to publication.