W-9 for winning a prize as a J-1 research scholar from Germany

[germanInUS]

Hi,

it's been a while since the last post I have left the US after less than 183 days, so I am a non-resident alien in 2020.

Then they evidently do not understand U.S. tax law as well as they should. They were obligated to withhold the 30%. Since they didn't, you will need to file a return and pay that tax on your 1040-NR.

Unfortunately the contest staff did not send me any forms or other documentation about the prize. They also did not reply to my e-mail asking for documentation. Should I still include it in the 1040-NR and if yes, in which field would it go? My tax agency recommended not to include it since I have not received a form 1099.

They should give you a Form 1099 next January for the award. That's how the IRS will know you got it. If you don't report it on the return and don't pay the tax you will be subject to penalties and potentially additional withholding, too.

It is possible that they sent it to my old US address and the people who live there now threw it away. If they did that and I do not include it in the 1040-NR, will the IRS just notify me about the mistake and I need to pay or will there be serious penalties? If yes, what would that be?