I think the way it works now is that the minimum duty is 15%. But the duty schedule is still used to calculate the amount owed.
Still using the HTS duty schedule to calculate the amount due, if the total is under 15%, then the 15% tariff applies.
If the HTS duty schedule determines the amount owed is 15% or more, then there is no additional tariff.
"For an article the product of Switzerland or Liechtenstein with a Column 1 Duty Rate that is less than 15 percent, the sum of its Column 1 Duty Rate and the additional
ad valorem rate of duty pursuant to this notice shall be 15 percent
ad valorem. For an article the product of Switzerland or Liechtenstein with a Column 1 Duty Rate that is at least 15 percent, the additional
ad valorem rate of duty pursuant to this notice shall be zero."
Source:
https://www.federalregister.gov/doc...elated-elements-of-the-framework-for-a-united
Caveat is I am not a lawyer or anything near knowledgeable regarding tariffs and duties. This is how I interpret it and I am happy to be proven ignorant on the subject.