What Will Happen if You Use a USPS Flat Rate Box With a Non-flat Rate Shipping Label
The United States Postal Service (USPS) offers two types of shipping rates: regular rates, which are charged according to weight and shipping zone, and flat rates, which are charged at a fixed price depending on the type of box used. What would happen, though, if you created a non-flat rate shipping label and put it on a flat rate box? Would the label or the box take precedence?
USPS expedited services, Priority Mail and Priority Mail Express, offer both flat rate and standard (non-flat rate) pricing. With standard pricing, the shipping cost is calculated based on package weight and shipping zone, reflecting the package’s travel distance. Packages are charged by either gross (actual) weight or dimensional weight, whichever is higher. Therefore, every package must be weighed and measured before shipping.
The USPS introduced flat rate pricing to make things easier for customers who don’t want to bother weighing and measuring their packages. They offer a variety of flat rate envelopes and boxes with fixed shipping prices. All you need to do is choose the one that fits your items. The boxes and envelopes themselves are free; their cost is included in the shipping price. USPS flat rate packaging is clearly labeled with the words “Flat Rate” and the name of the delivery service, either Priority Mail or Priority Mail Express.
Imagine you have a USPS flat rate box that will fit the items you’re shipping, but you don’t want to use flat rate pricing because standard rates would be cheaper. Your plan is to pack the items in the flat rate box and print a non-flat rate shipping label, calculating the shipping cost based on the package’s weight. Will this plan work?
Sadly, it won’t: USPS flat rate boxes can only be used for flat rate shipments, no exceptions. If you take a flat rate box with a regular shipping label to a Post Office, it will be rejected at the counter. You will have to either repackage the items in another box or pay for flat rate shipping.
If you drop off a package at a USPS location that does not require interaction with a USPS employee (such as a Post Office drop-off area, USPS collection box, self-service kiosk, or gopost unit), there are two possible outcomes. The package may be returned to the sender, or it may be delivered, but you will be billed the difference between what you paid and the flat rate price. In the latter case, the shipment may be delayed because the shipping price will need to be recalculated.
In summary: you can only combine a USPS flat rate shipping box with a matching flat rate shipping label that corresponds to the type of flat rate packaging you used. For example, you must use a Priority Mail Flat Rate Small Box label with a Priority Mail Flat Rate Small Box. If you choose to ship by weight and print a regular shipping label, you can use any box, except a flat rate box. If you have unused flat-rate boxes and don’t need them, you can donate them to the post office.