Korea publishes its allowances as actual numbers, which makes this one of the easier customs regimes to prepare for. It is worth doing, because the penalty structure is less forgiving than the allowance suggests.
Everyone fills in the form
All travelers arriving in Korea must submit a personal effects declaration form to customs officials. There is no version where you skip it.
If you have goods to declare, you are expected to do so voluntarily on arrival. If you have nothing to declare, you may use the “Nothing to Declare” channel.
The allowance, in numbers
Personal effects: US$600 total value. That is the overall cap, and it is separate from the specific items below.
Cigarettes: one carton, meaning 200 cigarettes.
Liquor: one bottle, up to 1 liter and up to US$400 in value. Both limits apply, so an expensive bottle can breach the value cap while staying under the volume cap.
Perfume: up to 60 ml.
Travelers under 19 face restrictions on the liquor and cigarette allowances.
The rule that costs people money
If the volume or weight of a single item exceeds the duty-free allowance, the total price of that product becomes dutiable, not merely the excess.
This is the opposite of how most people assume customs works. Going 20 percent over does not mean paying duty on 20 percent. It means the whole item is now dutiable. That changes the arithmetic on buying one large bottle versus staying inside the limit.
If you are bringing food or traditional medicine
Agricultural, fishery, livestock and oriental medicine items are treated as a group, with the total weight required to stay under 40 kg.
Specific per-item limits also apply to traditional medicine materials such as ginseng and deer antlers. Those figures sit in a table on the official page and are the kind of number worth reading at the source rather than from us. The link below goes to it.