Using "care of" in an address comes up more often than most business writers expect: forwarding a contract to someone staying at a colleague's office, sending a package to an employee through a company, or mailing a legal document to a person through their attorney. The abbreviation c/o does the work in every one of these situations, but only if you write it in the right place and understand what it actually tells the postal carrier or the receiving party.
What "care of" means
"Care of" (abbreviated c/o) signals that the intended recipient does not permanently reside or work at the address you're using. The person or organization listed after the address belongs to the location; the person listed before c/o is a guest or a temporary resident who can be reached through them.
Think of c/o as an instruction to an intermediary. You're telling the post office, and then the person at that address: "Please get this to the person named above you on this envelope." The intermediary passes the mail on. Without the abbreviation, a letter addressed to someone unknown at that location is likely to be returned or discarded.
When to use c/o in an address
There are four common situations where "care of" belongs in a mailing address.
- Sending mail to someone through a business or organization. A freelance contractor who receives checks at their client's office is a classic example.
- Sending mail to a person staying temporarily at someone else's home. A relative visiting for an extended period, or a short-term lodger without a lease, fits here.
- Routing legal or financial correspondence through a representative. Attorneys, accountants, and registered agents often receive mail on behalf of their clients this way.
- Shipping to an employee at their employer's address. When a remote worker has equipment delivered to headquarters, the package often carries their name c/o the company.
If the recipient has their own permanent address, skip c/o entirely. The abbreviation exists for intermediary situations, not as a stylistic flourish.
How to format a care of address
The format is straightforward, but the line order matters. Write the intended recipient's name on the first line. On the second line, write c/o followed by the name of the person or organization at that location. Then write the street address, city, state, and postal code in the lines that follow.
Here's a concrete example:
Jordan Rivera
c/o Meridian Legal Group
400 Park Avenue, Suite 1200
New York, NY 10022
Jordan Rivera is the intended recipient. Meridian Legal Group is the intermediary who will pass the correspondence along. The building and suite belong to the law firm.
A second example, for a personal address:
Sam Okafor
c/o Priya Okafor
18 Linden Street
Austin, TX 78701
Sam Okafor is staying at Priya Okafor's home. The house belongs to Priya. Sam is the person the sender is trying to reach.
Capitalization and punctuation for c/o
Write the abbreviation as c/o in lowercase. The slash takes the place of the word "of," so no spaces sit on either side of it. You don't need a period after the o, and you don't capitalize the c unless it opens the line and your house style capitalizes all address lines (some formal business templates do).
Both c/o and the spelled-out form "care of" are correct. In most business and postal contexts, c/o is preferred because it's compact and universally recognized. The spelled-out form appears more often in formal legal documents or when the writer wants to avoid any ambiguity.
Don't add a comma between the recipient's name and the c/o line. The two lines read as a unit, and a comma would imply a clause relationship that doesn't exist here.
Common mistakes to avoid
The most frequent error is reversing the order of names. Writers sometimes put the intermediary's name first and the intended recipient's name second. That sends the letter to the wrong person. The recipient you want to reach always goes on line one.
A second common mistake is using c/o when the recipient has a direct address. If someone works permanently at a company, their name followed by the company's address is all you need. Adding c/o in that case is redundant and can slow down delivery if postal workers interpret it as a third-party routing instruction.
Don't confuse c/o with ATTN: (attention). "Attention" directs a package or envelope to a specific person within an organization that already receives general mail at that address. A company ordering supplies from a vendor might ask the vendor to write ATTN: Purchasing Dept. on the box. c/o is for individuals who are not the primary occupant of that address.
How c/o appears in email and digital contexts
In email, "care of" doesn't appear in the address field itself, since email addresses route directly. But c/o does occasionally appear in the body of an email or in a document header to indicate that a physical mailing should be routed through a third party. When you're drafting a letter to be printed and mailed, and you include the recipient block at the top of the document, format it exactly as you would on an envelope.
For a broader look at how to format different types of addresses in business documents, the guide on how to write an address across multiple types covers mailing labels, email signatures, and formal letters in detail.
International addresses and c/o
The abbreviation c/o is widely recognized across English-speaking postal systems, including those in the United States, the United Kingdom, Canada, and Australia. For international mail sent to non-English-speaking countries, check whether the destination country's postal service recognizes the Latin abbreviation. Some countries use local equivalents. France uses chez. Germany uses bei. When mailing internationally, spelling out "care of" or consulting the destination country's postal guidelines reduces the risk of misdelivery.
The United States Postal Service accepts c/o as a standard address element and processes it without issue for domestic mail.
A note on registered agents
In corporate and legal writing, c/o frequently appears in connection with registered agents. A registered agent is a person or entity designated to receive legal documents on behalf of a business. If your company's registered agent is a separate firm, any official correspondence addressed to your company routes through that firm using c/o. This usage is legally significant: courts and government agencies depend on the address chain being correctly formatted so that service of process reaches the right party.
Getting this detail right matters in ways that go beyond postal etiquette. A misaddressed legal notice can create genuine procedural problems. When drafting these addresses, double-check both the recipient's name and the intermediary's name before sending.
If you're also working on other fine points of professional correspondence, it's worth reviewing how to address multiple people in an email or letter, since those situations introduce their own formatting decisions that are easy to get wrong.