This is new to me, as I’ve never bought anything overseas and brought it back while traveling. Is it illegal to travel overseas with a worn out or generic bag, buy a new nice back while overseas, throw away the old bag and continue on like nothing happened? Why would you be required to declare something you bought as a replacement? I don’t know the import laws, but it seems to go against common sense to pay an import duty for a replacement bag. I can understand if you bought an additional bag and came back from overseas with 2 bags.
This isn't logical at all.
First of all, if you go overseas with let's say a Baggu, and throw that Baggu out and come home with a new one, that's so far under your $800 exemption that it's a nothingburger,
but you are still importing a new Baggu into the US.
If you go overseas with a Baggu, and you toss that out and buy a nice new Birkin (or any bag over $800),
you are importing the new Birkin/new bag into the United States above your exemption and therefore pay customs duties on such import.
In addition, if you are coming from a country or region that refunds sales/VAT tax, you will normally have taken this tax refund prior to entering the US. The logic here is that
you were refunded tax because you were exporting the bag, so
you must pay tax when importing the bag.
It's about import/export, not about your personal collection and how many bags you have.
You
are allowed to import used personal goods into the US that were acquired overseas, so, if you want to buy a bag in let's say Paris, keep it there for a year* and use it, then yes, it's a personal effect and can be brought to the US as such without duties.
You are not entitled to a tax refund from country of origin in this case.
*there is an actual period of time for this, but I do not recall exactly - believe it is under a year.