Tax
Under the FIFO principle (First In, First Out), a partial sale is treated for tax purposes as selling the earliest purchased shares first.
The FIFO principle (First In, First Out) determines which shares count as sold for tax purposes in a partial sale: the earliest purchased shares are sold first.
An example: you bought 100 ETF shares each in 2020 (price 80 EUR) and in 2023 (price 120 EUR). When you sell 100 shares, the 2020 tranche with the higher capital gain is typically the one treated as sold.
Investors who want to manage FIFO can spread their shares across different brokerage accounts. That makes it possible, depending on the situation, to sell the more tax-efficient shares deliberately.
See taxes, dividends and allocation for your whole portfolio in one place.