Guides
Import duty, HS codes and tariffs — explained plainly
Sourced, jargon-free guides to classifying products, reading the tariff schedule, and calculating the real landed cost. Every rate we quote links back to the official schedule of record.
What is llms.txt — and why customs tools need one
llms.txt and the Model Context Protocol let AI agents find and call live data instead of guessing — vital when tariff rates change monthly.
July 12, 2026 · 8 min read
Best HS code classification APIs in 2026: how to choose
How to evaluate an HS code classification API in 2026: reasoning transparency, sourced rates, Chapter 99 stacking, rate limits and MCP support.
July 12, 2026 · 11 min read
IOSS registration for EU sellers: a step-by-step guide
Shipping to the EU? IOSS lets you charge VAT at checkout instead of surprising buyers at delivery. Who needs it, and how registration actually works.
July 12, 2026 · 10 min read
Continuous customs bond: cost and coverage guide
When does a continuous customs bond beat single-entry bonds? A cost comparison, what CBP Form 301 covers, and who is actually on the hook for it.
July 11, 2026 · 10 min read
Auto parts tariff: Section 232's 25% explained
Section 232 added a tariff on cars and auto parts, but not every part on your invoice is in scope. How the measure works, and how to check your line.
July 11, 2026 · 10 min read
Copper tariff 2026: Section 232 rates and scope
A newer Section 232 measure reaches copper — cathode, wire, tubing and fittings. Here's how the mechanism works and where to verify the current rate.
July 10, 2026 · 8 min read
The Section 301 exclusions list: how to check yours
How Section 301 exclusions work, where USTR publishes the current list, and the exact steps to check whether your HTS line and product qualify.
July 10, 2026 · 10 min read
9903.88.03 and Chapter 99 codes, explained
How 9903.88.xx modifier codes work, why they must be filed alongside your normal HTS line, and what happens to your duty bill if you leave one off.
July 9, 2026 · 9 min read
Entry Type 86 vs formal entry: which do you need?
De minimis and Entry Type 86 are suspended. Here's how to tell whether informal or formal entry applies to your shipment, and what each one costs.
July 9, 2026 · 10 min read
Duty drawback: what it is and how to claim it
Duty drawback refunds up to 99% of duty paid on goods later exported or destroyed. Who qualifies, the three claim types, and the five-year filing window.
July 8, 2026 · 9 min read
Importer of record: who is it, what do they owe?
Every US shipment needs a legal importer of record. Here's who can hold that role, what obligations they carry, and why the wrong choice gets expensive.
July 8, 2026 · 8 min read
What is DDP shipping — who pays the duty?
Under DDP shipping the seller pays the duty, baked into the price, cleared before delivery. How DDP differs from DAP and EXW, and what sellers must set up.
July 7, 2026 · 8 min read
Did the Supreme Court strike down IEEPA tariffs?
Yes — on 20 Feb 2026 the Court ruled IEEPA doesn't authorise tariffs. What that means for duties already paid, and the Section 122 tariff that replaced them.
July 7, 2026 · 10 min read
Does USMCA exempt you from Section 122?
Qualifying USMCA goods from Canada and Mexico skip the Section 122 surcharge — but only with a valid certificate of origin. Here's what actually counts.
July 6, 2026 · 8 min read
Section 122 tariff explained: the new baseline
Section 122 of the Trade Act of 1974 now backs a baseline import surcharge layered under Section 301 and 232 tariffs. How it works and where to verify it.
July 6, 2026 · 10 min read
Is $800 De Minimis Still Available? What Changed in 2025–26
No — de minimis is suspended worldwide, with elimination due 2027-07-01. The full timeline, what it means for Entry Type 86 filers, and what to do now.
July 6, 2026 · 9 min read
How to find the HS code for your product
The complete method for HTS lookup: how the schedule is structured, where to search, how the GRI resolve disputes, and mistakes that cost real duty money.
July 6, 2026 · 11 min read
China Tariff 2026: How Section 301 Import Duty Stacks
Import duty from China to the USA is layered, not one number: base HTS rate, Section 301 and more stack together. Here's where to check your real rate.
June 24, 2026 · 9 min read
What is landed cost and how to calculate it
Landed cost is the true all-in cost of an import — product, freight, duty and fees. Here's the formula, a worked example, and the costs people forget.
June 10, 2026 · 10 min read
Harmonized Tariff Schedule (HTS) — a plain-English guide
The HTS is the official list of every product the US imports and the duty on each. How it's structured, how to read a duty rate, and where Chapter 99 fits in.
May 14, 2026 · 10 min read
How US import duty is calculated (with a worked example)
Import duty isn't one number — it's a stack. See the exact calculation, from customs value to final bill, with two full worked examples.
April 30, 2026 · 9 min read
MPF and HMF: the customs fees importers forget
Beyond duty, CBP charges two fees on imports: the Merchandise Processing Fee and Harbor Maintenance Fee. Rates, minimums, and how customs value is set.
April 16, 2026 · 10 min read
Section 232 steel & aluminum tariffs explained
How the Section 232 steel and aluminum tariff works, what counts as a covered derivative product, and how to check whether your HTS line is caught.
April 2, 2026 · 10 min read
How AI agents classify products and compute landed cost
A developer's guide to PortRobin's customs API and MCP server: turn a product description into a sourced HTS code and landed cost an AI agent can trust.
March 19, 2026 · 11 min read
HS code vs HTS code vs Schedule B — the difference
HS is the 6-digit global root, HTS is the 10-digit US import code that sets your duty rate, Schedule B is the export code. Which do you need?
March 5, 2026 · 10 min read
How to avoid overpaying import duty (legally)
Most importers overpay duty through inertia, not fraud — a stale HS code, a missed trade preference, an unclaimed refund. The legal playbook to fix it.
February 19, 2026 · 10 min read
Country of origin: why it decides your tariff
Country of origin, not where you bought the goods, decides which tariffs apply. How CBP determines origin and what substantial transformation means.
February 5, 2026 · 9 min read
Classify a product and see its real duty
Describe any product to get its HS/HTS code with the reasoning, the sourced duty rate including Section 301 and 232, and the full landed cost.