What Is Address Line 2? Meaning, Examples, and USPS Rules

What goes in address line 1 and address line 2

Address line 1 holds the street number and street name. Address line 2 holds the unit. The table below shows both, plus the same address written on one line the way USPS prefers. USPS says “Uppercase letters are preferred on all lines of the address block,” so the last column uses capital letters.

The addresses in the table are samples.

Section 213.1 of Publication 28 lists the most common unit words: APT, BLDG, FL, STE, UNIT, RM, and DEPT. Appendix C2 has the full list. Some words in that list need no number after them, including BSMT for basement, FRNT for front, PH for penthouse, and REAR.

Lines 1 and 2 describe how one address is written. Whether a form wants your mailing address or your physical address is a different question. Our guide to mailing address vs physical address covers that one.

What USPS says about apartment and suite numbers

USPS covers unit numbers in section 213 of Publication 28. The rule reads: “Secondary address unit designators, such as APARTMENT or SUITE, are required to be printed on the mailpiece for address locations containing secondary unit designators.” So if your address has a unit, the unit belongs on the mail.

The same section says where the unit goes: “The preferred location is at the end of the Delivery Address Line.” USPS’s examples follow that rule, as in 102 MAIN ST APT 101 on a single line.

USPS gives a second choice for when the full line does not fit. Section 213.3 says: “If all Delivery Address Line information cannot be continued in the Delivery Address Line above the city, state, and ZIP Code, place secondary address information on the line immediately above the Delivery Address Line.” In the USPS example, APT C sits on its own line directly above 5800 SPRINGFIELD GARDENS CIR.

A web form shows line 2 below line 1, which is a different order from both USPS options. How a company prints your address on a label is up to that company. When you write or print an address yourself, put the unit at the end of the street line. Use the line above the street only if the unit does not fit.

USPS also has a rule for the pound sign. Section 213 says “The pound sign (#) should not be used as a secondary unit designator if the correct designation, such as APT or STE, is known or is shown in the ZIP+4 file.” If you do use the sign, “there must be a space between the pound sign and the secondary number,” as in 425 FLOWER BLVD # 72. A private mailbox address follows a separate USPS section, section 285.

What to do when a form has only one address line

Put the whole street address on that line, with the unit at the end, as in 1356 Executive Dr Ste 202. That placement is the USPS preferred location, so you do not need a second line.

IRS Form W-9 works this way. The form has a single line for the street and the unit, labeled “Address (number, street, and apt. or suite no.). See instructions.” The form’s instructions for line 5 say: “Enter your address (number, street, and apartment or suite number).”

IRS Form 1040 gives the unit its own small box. One box is labeled “Home address (number and street). If you have a P.O. box, see instructions.” A separate box is labeled “Apt. no.” Read the label and put the unit where the label asks for it. If a form has a separate line 2 or unit box, use that box.

A comma between the street and the unit is optional for USPS. Publication 28 says “With the exception of the hyphen in the ZIP+4 Code, punctuation may be omitted in the delivery address block.” If the box is too short, use the USPS abbreviations, such as STE for suite and APT for apartment.

Our guide to entering a suite number on online forms covers how to write Suite, Ste, or # on forms that check your entry.

What does not belong in address line 2

Line 2 is for the unit. USPS treats three other kinds of information differently, so keep them out of that line.

• A second address. Publication 28 says “Eliminate dual addresses on the output mailpiece, if possible,” and it adds that if two addresses are used, you should “place the intended delivery address on the line immediately above the city, state, and ZIP+4 Code.” A P.O. Box typed on line 2 under a street address can end up on that line. If a P.O. Box is your only address, enter it on line 1, because USPS uses the box number in place of the street and number.
• A name or attention note. Publication 28 says “The Attention Line is placed above the Recipient Line, that is, above the name of the firm to which the mailpiece is directed.” If a form has a Company or Attention box, use that box.
• Delivery notes. Directions such as “use the side door” are extra text in an address. Publication 28 says “Printing complete information on a mailpiece and eliminating extraneous information that can confuse delivery personnel or be misread by postal equipment does a lot to get the mail delivered on time.” If a form has a delivery notes box, put them there.

What happens if you leave address line 2 blank

If your address has no unit, nothing is missing. The USPS rule covers “address locations containing secondary unit designators,” and an address with no unit is not one of those.

If your address does have a unit, leaving it out makes the address incomplete. The Domestic Mail Manual (DMM), the USPS rulebook, lists the “Secondary address unit designator and number” as part of a complete delivery address.

Mail without the unit can still arrive in some cases. USPS’s FAQ on undeliverable mail answers the question “Why was my mailpiece returned for a missing apartment number?” The FAQ says the Postal Service “encourages the use of apartment numbers,” and that “mail will be delivered if any one of the following elements is present”:

• Apartment number is included on the envelope.
• Recipient's name appears on or inside mail receptacle.
• Recipient's name appears on an alphabetical directory furnished by the apartment management.
• The mailperson recognizes the information and remembers the correct apartment number.

USPS wrote that list for apartment complexes. Only the apartment number on the envelope depends on what you type into a form. The rest depend on the mailbox label, the building’s directory, or the carrier’s memory.

If a package comes back or tracking shows “Insufficient Address,” our guide to that status when the address is correct explains where to check.

If you are not sure whether your building uses unit numbers, try our free address checker. The checker can show a note when a building uses suite or unit numbers and your entry has none. The checker does not confirm that a given unit number is yours.

What to put in address line 2 if a form requires it

A form may refuse to continue while line 2 is empty, even if you have no unit. Publication 28 is written for addresses on mail and in address lists, so the company that runs the form is the one to ask.

Contact that company and ask what it wants in the box. Do not make up a unit number. USPS defines a complete address as one with the elements needed for “an exact match” with its ZIP+4 and City State files. A made-up unit adds an element that does not belong to your address.

Typing filler such as “N/A” or a dash carries a risk too. If the company prints that text on a label, it becomes the kind of extra information Publication 28 warns about.