The tournament regulations normally state this. If you are a law-obedient person, make sure you study them carefully and check this with the organizers. Most of them leave it to the prize-winners to pay the taxes themselves.
Paying the chess tax

I would imagine it's a lot like poker, where you can deduct your winnings against your entry fees. See, if you play in 5 tournaments each with an entry fee of 100$, and then in tourney #5 you win 500$, you're not really ahead.
Consult your local tax professional for advice.

In the US, tournaments must report any prize won over a certain limit (I think it is $600) to the IRS.
In the US, if an individual's total gross winnings for the year exceeds $400, it must be reported to the IRS through the annual income tax return.

Chess players should not have to pay any taxes. It is totally unjust because so many players are starving in order to play.

If you are truely starving then you probably don't make enough to pay taxes anyway...at least in the US.

Are winnings from chess tournaments taxable? Like if I don't pay income tax for them will I become a criminal? Help!