I used poloniex.
Anyone know if poloniex submitted any information?
yeah but did you use coinbase to cash out bitcoins to USD? that seems to be the common thread among those receiving the IRS letters.
since Poloniex is based on US already, then it is best if you assume that they have reported your history to the different government agencies. even if they haven't it should always be a possibility that they will do in an instant upon request.
unlike coinbase, poloniex does not send the 1099-K. they don't voluntarily report anything to the IRS:
https://twitter.com/Poloniex/status/1091724304138600448the letter writing campaign is clearly a fishing expedition. if the IRS has already gone to the lengths of subpoenaing exchanges for your records, you're probably getting audited and criminally charged---not receiving a warning letter telling you to amend your tax return.