In the guide issued by the Korea Customs Service for travelers' carry-on items, it explains a situation in a Q&A format to prevent travelers from facing unfair situations in terms of taxes when they carry items exceeding the duty-free limit upon departure and then bring them back upon re-entry.
The Korea Customs Service refers to this situation as 'double taxation,' but from my perspective, it doesn't seem to be double taxation.
It's simply that when you carry these items and enter another country, you pay the taxes of that country if you exceed the duty-free limit according to that country's laws, and when you bring them back to Korea, you pay customs duties according to Korean laws for exceeding the duty-free limit. Therefore, it's just that the conditions for collecting taxes according to each country's customs laws are met.
However, from a traveler's perspective, it may seem like 'double taxation' since they are paying taxes twice on the same item.
Anyway, here is an excerpt from the Korea Customs Service's guide.
□ Items purchased at domestic duty-free shops upon departure and brought back to Korea, items acquired overseas(purchased·gifts, etc.), and the total price of items purchased at duty-free shops upon entry exceeding US$800 are subject to voluntary declaration, and in this case, taxes must be paid to bring them into the country..
[Example]
If the individual prices of items purchased at domestic duty-free shops and overseas are US$200, US$400, US$500 each
: Although no individual price exceeds the duty-free limit(US$800), the total price of the items is US$ 1,100, so they are subject to customs declaration
□ Even if taxes have been paid on items purchased at domestic duty-free shops upon departure when entering the local area overseas, if you bring them back to use in Korea , Korean customs duties will be imposed.
Therefore, when entering the travel country with items purchased at domestic duty-free shops that exceed the travel country's duty-free limit , you should use the temporary storage(deposit) system to avoid tax burdens locally.