Becoming an authorized user can help you build credit. But here are the risks.

An authorized user is someone you trust to spend on your credit card who can piggyback on your credit to build – or restore – his or her credit history. The authorized user can access credit without applying for a card, and your on-time payment history will show up on the user’s credit report, as long as the card reports to credit bureaus.

“Typically, the entire account history will show up on the authorized user’s credit report,” says Gerri Detweiler, credit expert and author of six books, including “The Ultimate Credit Handbook.” “If the primary cardholder has a good payment history and low debt, that can be a tremendous benefit.”

The practice of adding an authorized user to an account has pros and cons for both parties. Here’s more about the risks and the payoffs before proceeding.

An authorized user has permission to make purchases on someone else’s credit card but is not liable for card payments. Typically, authorized users on personal credit cards are family members or trusted friends. Legally, authorized user status has no minimum age requirement, but banks may set their own policies, according to Chase.

Authorized users usually pay for their card purchases, and payment arrangements are made between cardholders and authorized users. The authorized user is considered a secondary cardholder with access to an account but no ownership.

Authorized user status can help someone establish credit if the account is managed well. Full payment history is often reported to the three major bureaus, which is how authorized user status works to build credit. But the opposite is also true, and failure to use the card responsibly by either the authorized user or the cardholder can sink both credit scores.

While joint cardholders must apply for credit together and are both legally responsible for the bill, an authorized user has spending privileges on a card but is not liable for the balance.

Card issuers run credit checks on applicants for joint accounts, but they do not for authorized users. Generally, a primary cardholder only needs to reach out to the issuer by phone or online to add an authorized user to an account.

One person’s financial troubles could interfere with approval for a joint credit card. At the same time, someone with a lower credit score can take advantage of a co-applicant with a higher score to access better interest rates and higher credit limits on a card.

Joint cardholders share accountability for managing their card, even if one person pays the bills. One cardholder who misses a payment or runs up a balance can hurt the credit scores of both cardholders. Similarly, credit missteps by an authorized user or a primary cardholder can affect both people.

When a primary cardholder adds an authorized user to a card, that account will appear on the user’s credit report and can help that person build or restore credit if the account is managed well. The authorized user gains access to the primary cardholder’s credit line without a credit check and may receive his or her own credit card.

Adding a secondary user to an account should not be taken lightly and has pros and cons.

Many times, a primary cardholder will add someone to an account for shared access and for credit building. One example is a parent who adds a teen as an authorized user to learn how to make smart financial decisions before opening his or her own card.

Detweiler says, “I added my daughter as an authorized user to one of my credit cards when she turned 16 and started driving. She’s now in college and has an excellent credit score.”

A cardholder with an old and rarely used account may benefit from an authorized user to add positive payment activity and prevent closure. Your credit score can drop when an issuer closes a card.

Another reason to add an authorized user to an account in good standing is to help someone climb out of a credit hole.

“A lot of times, bad credit is not the result of shopping sprees,” says Ed Mierzwinski, senior director of the federal consumer program at the U.S. Public Interest Research Group, or PIRG.

Common reasons for poor credit, such as job loss and medical debt, can be difficult to predict or control.

Adding an authorized user to an account with the intent of establishing or increasing the user’s credit score is also known as piggybacking credit. However, paid piggybacking services can be expensive and are considered short-term solutions for improving credit scores.

If a cardholder has excellent credit and uses a card responsibly, becoming an authorized user on the account could give you a jump-start on building credit without having to apply for your own card. But you will need to confirm that the card issuer reports authorized user activity to credit bureaus. If the issuer does not, then card activity will have no effect on your credit.

The account holder and the authorized user must use the card wisely. If either one of you misses payments or racks up a lot of debt on the card, both of your credit scores can be damaged.

Ask someone you trust to add you as an authorized user. An authorized user will benefit most, according to Experian, from an account that:

If the cardholder is making mistakes that are damaging your credit, you can either ask the person to remove you as an authorized user or call the card issuer and request this change. Your score may drop a bit when you are removed as an authorized user, but you can improve it over time by using your own credit accounts responsibly.

Giving someone a credit card who would not otherwise qualify for one can be hazardous. You’ll want to weigh the risks of adding an authorized user to your card. Mainly, these are that you:

When you add an authorized user to your account, you are essentially asking that person to handle credit responsibly, Mierzwinski says. “If they renege on that promise, it can be difficult,” he says, “because you get the bad credit on your credit report.”

Authorized users can hurt your credit in two main ways, Mierzwinski adds. They can rack up a lot of debt, pushing you closer to your credit limit. Approaching your limit can cause your credit score to slip.

“As long as you’re paying your cards on time and staying below 30% of your limits, that’s good,” Mierzwinski says. “But if you go up toward getting maxed out, that’s bad.”

If the authorized user accumulates a lot of debt and struggles to pay his or her portion of the credit card bill, the primary cardholder will need to cover it. If you can’t, you may damage your credit.

“If you’ve got negative items – 30, 60 or 90 days late, or delinquencies worse than that – then the cardholder is hurt,” Mierzwinski says.

All of these issues can strain your relationship with the authorized user.

“It could all blow up if the two (cardholders) end up having a disagreement,” Mierzwinski says. “You’ve got to be pretty confident that you’re taking the right step.”

The primary cardholder can add the authorized user by calling the card issuer or logging into the online account. Each issuer has its own requirements but may need the authorized user’s name, address, birthdate and Social Security number to process the request.