Is purification required for dividend income even if tax is being collected for the dividends

As salam alaikum.

I have several stocks which provide dividends. And I saw many post explaining the necessity of purification for dividends.

However, dividends are taxable in the US. And that means dividends are reduced by 15% or 20% (depending on the income).

My question is, can the tax reduction be considered as purification? Since all halal stocks should only have less than 5% of haram source, 15% or 20% of tax reduction covers the required purification amount.

Jazak Allah.