I'm on H-4 visa and I partcipated in an online contest for instant prize but I won the first prize worth $3000.The Sponsor will send me the Tax form before the prize.my question is.. Is it legal to participate and win on H-4 visa?

Yes, it IS legal to claim the prize. Winning raffles or sweepstakes, trading stocks and bonds, getting paid a referral fee from your apartment compex are all activities permitted under your visa.

The only real restriction is that you cannot start a business nor can you work for someone else for pay.

Report the prize money on Line #21 of Form 1040 as "Sweepstakes winnings" and pay the appropriate taxes, and you should be fine.

Thanks a lot for a valuable reply!

Glad to help!