Question: If I already pay Zakat on my ETF investments, do I still need to purify my investment income? 

Answer:

Yes, you may need to do both, because Zakat and investment purification are two different obligations in Islamic law. Zakat is an act of worship imposed on eligible wealth when its conditions are met. Investment purification, on the other hand, concerns the removal of income earned from sources that are not permissible under Shariah. Although Zakat itself carries the meaning of purification, paying Zakat does not automatically make impermissible investment income permissible.

For example, suppose you own a Shariah-compliant ETF that generates dividends, a small portion of which comes from non-permissible sources. You may be required to remove that portion through purification while separately paying Zakat on your zakatable investments. Importantly, the amount given away for purification cannot be counted towards your Zakat obligation, as the two serve different purposes.

The distinction is therefore straightforward: Zakat concerns wealth that you rightfully own, from which a prescribed portion is distributed to eligible recipients (asnaf). Purification concerns income that you should not retain in the first place, which must instead be disposed of through appropriate channels. Depending on your investments and circumstances, both may apply.