A shipping address can look complete and still be missing one important detail: the apartment, suite, or unit number.
For a multi-unit building, the street address identifies the building, but a unit number helps identify where the package should go inside it. When that detail is missing, the carrier, recipient, or merchant may need to resolve it after checkout.
What can happen when a unit number is missing?
A missing apartment number does not always prevent delivery. The carrier may be able to identify the recipient using a building directory, mailbox, or other information. But that depends on what is available at the delivery location. The U.S. Postal Service explains that apartment numbers help with accurate delivery, while also noting other ways a recipient may be identified.
If the address cannot be completed, the shipment may need attention from the carrier, merchant, or customer. Address corrections can also cost the merchant. UPS’s 2026 Daily Rates and Service Guide lists a $25.25 address-correction charge per package for covered package services. FedEx’s 2026 Service Guide lists a $25.50 charge per correction for specified U.S. package services. Charges depend on carrier, service, and account terms.
There can be staff time involved as well. Customer-service teams may have to contact the shopper, research the missing apartment or suite, update the order, or coordinate with the carrier. That turns an address detail into follow-up work after checkout.
Address suggestions and address validation do different jobs
Address suggestions and device autofill can make it easier to enter a street address. But a street-level match does not necessarily confirm that the address includes the apartment, suite, or unit needed for delivery.
Address validation checks the address the customer entered and can flag details that may still be missing. For U.S. addresses, Addrexx can prompt a shopper when an address appears to need an apartment, suite, or unit number.
What the shopper sees
The prompt identifies an address that may be missing details, provides an Address Line 2 field, and lets the shopper choose whether to add information or continue without a change.
When the shopper adds an apartment, suite, or unit, that detail can be included before the order moves into fulfillment. The prompt gives the customer a chance to resolve the issue while completing checkout.
A practical checkout check for Shopify Plus merchants
Test a multi-unit address with the apartment number included, then test the same address without it. Confirm that checkout displays the expected prompt and that the customer can review and update Address Line 2.
If your store uses Shop Pay, include that checkout path in your review as well.
Addrexx provides checkout address validation for Shopify Plus merchants, including prompts for U.S. addresses that may be missing apartment, suite, or unit details.
Want to see how it works? Request an Addrexx demo.