Do I have to pay tax on my bets and winnings?

Yes the Tax Calculation is as follows for eg:- Withholding Tax (WHT) = 0.20*(Gross Winnings - Stake)
Excise Duty = (0.20*Stake).

For Eg:- To place a bet of KES 20.00, you'll require an account balance of KES 22.00; an additional KES 2.00 which is 10% of KES 20.00,