USPS changed its International Mail Manual on October 19, and the rule is already in effect. If a destination customs authority, postal operator, broker, or representative seeks unpaid duties, taxes, or import fees on an international mailpiece, USPS can invoice the US mailer for the amount.

Postage does not cover those foreign customs charges. The invoice can arrive after you bought the label, and the rule says you still pay even if the parcel was delivered, lost, damaged, or returned.

When the Invoice Can Arrive

The interim final rule responds partly to the EU's July 1 customs changes and to the different collection practices destination postal operators have adopted.

Some destinations require approved delivered-duty-paid service for certain shipments. Others try to collect from the recipient first, then pursue the sender or USPS if the recipient does not pay.

The rule does not say every international package generates another bill. It establishes mailer liability when applicable amounts remain unpaid and a relevant foreign party seeks collection. USPS Delivered Duty Paid service can be used where available, but the mailer stays responsible for complete customs information and destination requirements.

A low duty rate does not mean zero customs cost. The rule says import fees can come from brokers, postal operators, government agencies, and other service providers, and can apply even when duties and taxes do not.

You Pay First, Then Dispute

If USPS invoices you, section 424 says you must pay the entire amount by the invoice deadline even while disputing the foreign assessment. A late amount accrues interest at 6% per year, and USPS can pursue collection costs where the law allows.

Your dispute rights with USPS are narrow. You can challenge an accounting error in the USPS invoice itself. If you believe the foreign customs authority or postal operator calculated the duty, tax, or fee incorrectly, you take that to the foreign party without USPS involvement.

If USPS later receives a cancellation, credit, or refund, the rule says it will make a corresponding adjustment if USPS considers that practical, except for amounts properly due or nonrefundable. That wording does not promise a fast or automatic credit.

A Return Does Not Close the File

The operational risk shows clearest on a refused order.

You may refund the customer, pay return transportation, and later receive a customs invoice tied to the same parcel. The rule specifically says loss, damage, or return does not erase the payment obligation.

This does not make USPS responsible for foreign customs policy. It formalizes how USPS passes an unpaid foreign assessment back to the mailer. The practical lesson is that whoever appears as responsible for charges has to match the service, the customs declaration, and the customer promise.

How product classification and customs paperwork affect duty is useful preparation, though its examples are background rather than guidance on outbound mail. How shipping terms allocate cost and responsibility helps frame DDP, but an Incoterm does not replace a destination's postal requirements.

Build the Control Before the Next Batch

List every country you serve through USPS and identify whether the destination requires DDP for your product and transaction type. Confirm the accepted service with USPS or your postage provider rather than assuming a checkout tax setting produces a compliant DDP shipment.

Audit the data feeding the customs form. Product description, HS code, country of origin, value, and required certificates should come from a maintained product record. Do not let a warehouse shorten descriptions to “gift” or “sample” when that does not match the commercial order.

Create a shipment-level customs reserve for destinations where assessments can be passed back. Keep label records, customs forms, commercial invoices, delivery status, and customer communications under one shipment ID. If an invoice lands months later, you need enough evidence to identify the order and the foreign party behind the charge.

USPS is accepting comments until November 18. Sellers and shipping platforms with concrete examples of billing delays, dispute barriers, or data mismatches have a short window to put those into the public record.

Meanwhile, treat the rule as effective now and keep closed international orders reconcilable after delivery.