With derivatives on US underlyings, tax may be levied on the derivative in the event of a dividend payment in the underlying due to what is called a dividend-equivalent payment. This particularly affects what are called delta-one derivatives such as knock-out certificates or mini futures, but can also affect warrants with a delta above 0.9. This is due to IRS Regulation 871(m), which establishes a withholding tax for these dividend-like payments. The rule does not apply to short products, and is only applicable to underlyings registered in the United States. Furthermore, derivatives on fixed indices such as the Dow Jones Industrial Average, the S&P 500, and the Nasdaq-100 are excluded.
In the event of such a tax-relevant payment, the issuer of the derivative retains 30% US withholding tax and adjusts the properties of the derivative, such as the strike, accordingly. If you are subject to a 15% US withholding tax rate based on the double taxation agreement, Trade Republic automatically reimbursements you any excess tax paid, and you don't have to do anything else. You can find information about any possible refunds in your profile.