What you paid to buy, including the fees
This is the figure subtracted from the sale price to work out a gain, and it includes commission as well as the purchase price. How several purchases of the same stock are combined — averaged, or first in first out, for example — is fixed by each system. Without this number the size of the gain is undefined.
Where purchases are averaged, 100 shares at $1,000 and 100 at $1,200 average to $1,100, so selling at $1,300 is a gain of $200 per share.
Japan — In Japan several purchases of the same stock are averaged to give the acquisition cost.
South Korea — For Korean capital gains tax, when it is unclear which of several purchases of the same stock was sold, the earliest shares count as sold first (first in, first out, as of 2026). For foreign shares the National Tax Service also accepts the moving average a broker has applied consistently.
For learning, not investment advice. Decisions are your own.
StockFit · TrueNorthLabs Inc.