Most countries have their own law about paying taxes on casino winnings. If you are not sure of percentage or limits on tax deduction on winnings, please ask your local tax authorities.
The biggest winnings are usually found on progressive jackpot slot machines. You can see jackpots at tens of millions of dollars on Microgaming's Mega Moolah, or NetEnt's Mega Fortune several times a year.
Card counting is a very well known strategy in Blackjack that has worked for many players to break the bank of casinos around the world. But this strategy requires tremendous concentration, and with today's number of decks in use, it is almost impossible to achieve this without practicing hard every single day on such strategies.
At many online casinos today, you are offered several different bonuses at registration or on member promotions. To keep track of this and what bonus you want, they use codes. But if you forget this, it is usually easily arranged through the live chat center.
Free slots are best enjoyed at legitimate licensed sites that offer a good quality experience. If it’s a casino site it needs to be licensed in eth jurisdiction where you’re playing. An age check is a good sign that they take the law seriously.