How to Address an Envelope: Layout, Examples and What Trips People Up

You're holding a birthday card, a pen, and a blank envelope, and suddenly you're not sure what goes where. Learning how to address an envelope takes a minute once you know the three zones: recipient in the center, your return address top-left, stamp top-right. That's the whole map. The rest of this guide handles the parts that actually stump people — apartment numbers, PO Boxes, the IRS, and the four mistakes that quietly get mail sent back.

How to Address an Envelope: the Three-Zone Layout

Three zones. One rule holds them together: write so a machine can read it.

Here's the exact placement, per the USPS Letters guide:

1. Recipient's address — bottom center of the envelope face.
2. Return address — top-left corner, your info.
3. Postage — top-right corner, one valid stamp.

A rough sketch of the front:

```

[Return address] [STAMP]

top-left corner top-right

JORDAN MILLER

482 ELM STREET

FLUSHING NY 11354

(recipient, center)

```

The recipient block runs three lines. Line one: the full name. Line two: street address (with any apartment or suite designator). Line three: city, two-letter state abbreviation, then ZIP. Your return address follows the same three-line shape up in the corner.

Why the ALL-CAPS, no-commas look on official mail? USPS sorting equipment reads addresses optically, and clean block capitals with minimal punctuation scan faster and misread less often. Handwriting a personal card in normal case is fine — the post office still processes it. But for anything you want moving quickly, capitals help. When you buy first class stamps for these everyday letters, the stamp does its job only if the machine can read the address under it.

Recipient and Return Address Format

The recipient's name goes on line one exactly as you'd greet them — "Dr. Angela Ruiz," "The Nguyen Family," "Acme Tile Co."

Street address on line two. This is where the apartment question lives, so let's settle it: the unit number goes on the same line as the street address, not on its own line. Write 482 ELM STREET APT 3B. USPS prefers it appended after the street, using a secondary designator (APT, STE, UNIT, FL). Only bump it to a separate line directly above the city line if the street address is too long to fit — and even then, USPS would rather you keep it inline.

City, state, ZIP on line three. Use the ZIP+4 when you know it. The extra four digits point to a specific block or building, which shaves a step off sorting. You don't need it — five digits deliver fine — but USPS asks for it whenever you have it.

Your return address isn't optional decoration. Skip it and a letter that can't be delivered doesn't come back to you. It goes to a USPS mail recovery center (the modern "dead letter office"), where it may be opened to find an owner or, failing that, destroyed. Write the return address every time. It's the only way a misfire lands back in your hands.

Apartments, PO Boxes and Suites

Apartment or suite: append it to the street line — 1120 MARKET ST STE 400. Clean and scannable.

PO Box: replace the street line entirely with the box.

```

CASEY BROOKS

PO BOX 1847

FLUSHING NY 11352

```

Never list both a street address and a PO Box for the same recipient — the equipment routes to whichever line sits directly above the city, and you've now made that ambiguous. Pick one. If someone gave you both, the PO Box wins for USPS mail; a street address is for carriers and couriers like UPS or FedEx that don't deliver to boxes.

Couples, Families and Titles

Same last name, married or not: Mr. and Mrs. Leon Carter reads traditional; Alex and Sam Carter reads modern and works for anyone. Both are correct — pick the register that fits your relationship with them.

Different last names? Give each person their own line, alphabetical or by whoever you know better:

```

Priya Desai

James Whitfield

```

A whole household: The Okafor Family. And the grammar trap — it's The Smiths, not "The Smith's." You're making a plural, not showing possession. The Smiths. No apostrophe, ever, unless you actually mean something belongs to them.

Titles stack on line one before the name. Doctor: Dr. Angela Ruiz. Attorney: Angela Ruiz, Esq. (the Esq. goes after — don't use "Mr./Ms." and "Esq." together). For a gender-neutral honorific, Mx. works the same as Mr. or Ms.: Mx. Robin Vance. The Emily Post guide to addressing correspondence calls Mx. "the universal title that can be used by anyone," and USPS doesn't restrict honorifics — the machines read the address lines, not the greeting.

Business, ATTN and IRS Mail

Business mail adds a routing line most people get backwards. ATTN and c/o are not the same tool.

Use ATTN to steer a letter to a person inside a company that's already the right destination:

```

ATTN: ACCOUNTS PAYABLE

NORTHSIDE SUPPLY CO

900 INDUSTRIAL BLVD

LONG ISLAND CITY NY 11101

```

Use c/o ("care of") when the recipient doesn't normally get mail at that address — you're routing them through someone else's mailbox:

```

MARIA LOPEZ

C/O DANIEL LOPEZ

77 BAYSIDE AVE

FLUSHING NY 11358

```

Company name on the line below the person (or above, if the company is the primary target and the person is the ATTN). Job title, if you include one, sits with the name.

Mailing the IRS deserves its own note, because the format breaks the rules above. The IRS uses no street address for most mailed returns — just a city, state, and a special ZIP:

```

DEPARTMENT OF THE TREASURY

INTERNAL REVENUE SERVICE

KANSAS CITY MO 64999-0002

```

The exact processing center and ZIP depend on your state, which form you're filing, and whether you're enclosing a payment, so pull the correct address from the IRS "Where to File" page before you send. Mailing to the wrong center delays processing. And use certified mail if a deadline is involved — the postmark and receipt are your proof of timely filing.

Four Mistakes That Return Mail

These are the ones that cost you a trip back to the mailbox — or lose the letter entirely.

• No return address. Undeliverable mail can't come back. It ends up at a mail recovery center, not on your doorstep. Two seconds in the corner prevents this.
• Wrong or missing ZIP. The ZIP drives automated sorting. A missing or transposed ZIP kicks the piece to manual handling, which adds days, or sends it the wrong direction.
• Insufficient postage. Underpay and the letter comes back marked "Return to Sender" — or gets held for postage due. A 1 oz letter needs 82¢ as of the 12 July 2026 price change, and a standard postcard needs 65¢; a book of 20 Forever stamps runs $16.40 at face value. Our Forever stamp price guide tracks the current rates. Weigh anything thick or oversized — a wedding invitation with an inner envelope usually crosses into the two-ounce tier.
• International mail missing the country line. On overseas mail, the destination country must be the last line, alone, in English capital letters — FRANCE, not France tucked beside the city. USPS routes off that final line. Drop it and the piece stalls at the border. One Global Forever stamp covers a one-ounce letter to any country at a single price.

Pencil deserves a quick flag too. Calligraphers use light pencil guidelines and erase them, which is fine — but never address a live envelope in pencil that stays. It smudges, and faint gray scans poorly. Blue or black ink, always.

FAQ

Does the apartment number go on its own line?

No. Append it to the street line — 482 ELM STREET APT 3B. Only move it to a separate line above the city if the street address won't fit, which is rare.

Can I mail a letter without a return address?

You can, but you shouldn't. If it can't be delivered, it goes to a USPS mail recovery center instead of back to you, and may be destroyed.

How do I address an envelope to the IRS?

Use the processing center for your state and form — often just an agency name, city, state, and special ZIP with no street address. Confirm the exact address on the IRS "Where to File" page first.

Is it "The Smiths" or "The Smith's"?

The Smiths. You're pluralizing the family name, not showing possession, so no apostrophe.

Where does the stamp go on an envelope?

Top-right corner of the envelope's front face, opposite your return address. One valid stamp covering the correct postage for the weight and size.

Now that the layout's second nature, the last variable is what you stick in that top-right corner. At Mailboxes of Flushing we sell authentic, inspected postage sourced from closed businesses — real stamps at a lower cost, checked for unused, unbent condition before they ship. Browse our first class stamps for everyday letters, or a book of 20 if you mail regularly. We are an independent stamp reseller, not affiliated with USPS.