What Is a betting tax charged? 

We charge a 5% betting tax on all winnings. This means that if you place a bet, and it wins, we will withhold 5% of the winnings as tax. This will be deducted directly, and your account will only be credited with the winnings minus the tax. If your bet loses, no taxes will be deducted. You will find a corresponding note on the right side of the page below the betting slip before you submit it.  

You can find more helpful information about the betting tax here: https://hilfe.bildbet.de/hc/en-gb/articles/1500009769902-German-betting-tax-