Yes. One import can owe the regular (MFN) rate and one or more special duties at once, such as Section 301, Section 232 or anti-dumping and countervailing duties. Each comes from its own law with its own scope and dates, so each gets checked separately and the ones that apply are added up.
The base rate comes from the Harmonized Tariff Schedule. On top of it sit actions with their own authority. Section 301 duties come from 19 U.S.C. 2411. Section 232 duties come from 19 U.S.C. 1862. Anti-dumping duties come from 19 U.S.C. 1673 and countervailing duties from 19 U.S.C. 1671.
Each layer has its own list of covered goods, its own start date and often its own end date, and its own exceptions. A good can sit on one layer’s list and be outside another’s.
Whether two actions can both apply to the same good is decided by the text of those actions, so it has to be read for each pair rather than assumed in either direction.
In the Tariff Calculator, each layer’s percentage is applied to the same entered value, and the dollar amounts are added. A layer is not charged on top of the others’ duty. We checked this by running a $100,000 entry through the calculator: each layer’s dollars equalled its percentage times $100,000, and the total was the plain sum.
Where a layer cannot be settled from what we hold, the result shows it as unresolved and does not count it as zero, so the total reads as a floor, not a final figure.
Look at the layer-by-layer breakdown, not only the total. Each charged layer should show its own rate, its own authority and, where one applies, its own Chapter 99 filing heading. A layer you cannot trace to its own action is a layer to confirm before filing.
Section 301: 19 U.S.C. 2411. Section 232: 19 U.S.C. 1862. Countervailing duties: 19 U.S.C. 1671. Anti-dumping duties: 19 U.S.C. 1673. Base rates and Chapter 99 headings: Harmonized Tariff Schedule of the United States.
To see the stacked, cited answer for a specific entry date, use the free Tariff Calculator.