To add a Costco Anywhere Visa authorized user, log in to your online account and click “Services” under the “Account Management” menu at the top of the page. Next, select the “Authorized Users” option and enter the user's name, address, birthdate and Social Security number, before clicking “Add.” The Costco Anywhere Visa allows a maximum of 10 authorized users at no cost, but each person must be at least 18 years old and a Costco member.

If you prefer, you can add authorized users to your Costco Anywhere Visa account over the phone. Call customer service at 1 (800) 950-5114, enter your card number and respond to each of the automated prompts. Once you're connected to a customer service representative, be prepared to provide the required information for each authorized user you plan to add. Once added, authorized users will receive their own card within 10 business days.

Costco Anywhere Visa authorized users will be able to make purchases, up to the card's available credit limit. But as the primary cardholder, you'll have the ability to set a spending limit on each user's card. Authorized users can also earn rewards, report lost or stolen cards and view certain account information. They are not permitted to manage payments, however, nor can they add or remove other authorized users. An authorized user can contact Citi and request to be removed from the account at any time, though. The primary cardholder may also remove an authorized user from the account for any reason, with or without the user's consent.

Before you add a Costco Anywhere Visa authorized user, be aware you are responsible for any charges an authorized user makes. Plus, Citibank reports card activity to the three major credit bureaus once a month, so any negative entries will affect not only your credit, but also that of any authorized users on the account.