Here's How it Works. Or, at least, was supposed to Work Date-wise.
If your Tobacco Product was sold in a US Market On or Before Feb 15th 2007, it is Grandfathered. Nothing is Needed. Legal to Sell. Feb 15th 2007 is called the "Predicate Date".
If your Tobacco Product was sold in a US Market between Feb 16th 2007 and Aug. 8th 2016, then you were given 2 Years to Prepare/File a PMTA (or a SE or a MRT) for it. And you were Allowed to continue to Sell your Product while the FDA reviewed your application. This 2 Year "Grace Period" was extended by the former FDA Commissionaire. And then later rolled back in Court to what is now be Sept 9th 2020. Products sold between Feb 16th 2007 and Aug. 8th 2016 are referred to as "Existing Products".
If your Tobacco Product was Not Sold in a US Market On or Before Aug. 8th 2016, then it is considered to be a "New Product". And it Can Not Be Sold in a US Market UNTIL you receive a PMTA (or an SE or MRT) from the FDA.
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Where there is much Confusion is the FDA did Not Enforce the requirement for "New Products" that were Released after Aug. 8th 2016. They took a "Look the Other Way" approach.
So Technically, most of what the Average Vaper uses Today wasn't even supposed to have been Legal to Sell. Since Most of what people use Today came into the Market after Aug. 8th, 2016.
But the Long and the Short of it is Now we are about done with the Grace Period. And on Sept 9th your are going to have to have a PMTA (or Se or MRT) on file with the FDA to keep selling your Tobacco Product.
And you can Keep selling your PMTA-ed (or SE-ed or MRT-ed) Product for up to 1 Year. Or until the FDA either Approves your Product (Yah!) or Denies it (then it must be Removed from the Market).