What is anti-dumping duty?
The short answer: it's an extra import tax the US charges when a foreign company sells goods below fair value. Rates can hit 100% or more, and the bill often arrives after your goods do.
In one sentence
Anti-dumping duty (AD) is a penalty tax added on top of normal customs duty when the Department of Commerce finds that a foreign supplier is selling a product in the US for less than it sells for at home.
How AD stacks on top of everything else
A single shipment can carry four layers of duty at once. Most importers only plan for the first two and get blindsided by the third.
| Layer | What it is | Typical rate |
|---|---|---|
| 1. Normal (column 1) duty | Published HTS rate by product | 0% – 25% |
| 2. Section 301 tariff | Trade-policy tariff (e.g. China goods) | 25% – 100% |
| 3. Anti-dumping duty ⚠️ | Case-specific, set per finding | 0% – 500%+ |
| 4. MPF + HMF | Processing & merchandise fees | ~0.3% + 0.125% |
Layer 3 is where the cost gets away from people. It is also the one most importers never look up.
A concrete example
Say you import hardwood plywood from China. The HTS column-1 duty looks modest. But that exact product sits under an active anti-dumping order with a rate above 100%. On a $10,000 shipment the extra bill is another $10,000+. CBP collects it whether you knew about the order or not.
Why it catches people off guard
Normal duty is predictable. It lives in the HTS schedule, you can look it up. Section 301 tariffs are public too. AD/CVD does not work that way. Each order comes out of a specific case filed by a US industry, applies to a narrow set of products and countries, and the rate is set case by case.
The bigger problem is timing. The charge usually surfaces after the goods arrive. By then the shipment has sailed and the inventory is committed. Importers on Reddit and trade forums keep describing the same thing: a bill from customs long after they thought the deal was done.
Check your product before you order
Type a product name or HTS code. CVDar checks it against 1,200+ active AD/CVD orders. Free, no signup.
Check my product →Common questions
Is anti-dumping duty the same as a regular tariff?
No. A regular tariff (customs duty) is published in the HTS schedule and applies broadly by product category. Anti-dumping duty comes out of a specific case where the Department of Commerce found a foreign company selling below fair value, and it applies only to the products and countries named in that order. Both can apply to the same shipment, and they stack.
How high can an anti-dumping duty rate be?
There is no fixed cap. Many rates are in the single digits, but plenty run 50%, 100%, or several hundred percent. Hardwood plywood from China, for example, has carried rates well above 100%. The rate depends on how far below fair value Commerce determined the product was sold.
Who decides and enforces anti-dumping duty?
The US Department of Commerce investigates and sets the rate. The US International Trade Commission decides whether US industry is injured. US Customs and Border Protection (CBP) collects the duty at the border. New orders and rate changes are published in the Federal Register.
When do I find out I owe anti-dumping duty?
Often after the goods arrive. CBP may demand payment, or in some cases the bill comes months later through a retrospective review. That is why importers talk about 'surprise bills'. The charge was not visible at the time of purchase.
Can I check my product for anti-dumping duty before ordering?
Yes. You can look up active AD/CVD orders by product name or HTS code. CVDar matches against 1,200+ active orders from Federal Register filings. The free checker is at cvdar.com/tools/adcvd-checker.