I can post like 20 sources, but imo these are enough:
http://motherboard.vice.com/en_ca/read/irs-demands-identities-of-all-coinbase-traders-over-two-year-period
https://www.cryptocoinsnews.com/irs-targeting-bitcoin-transaction-records-coinbase-users/
https://goldsilverbitcoin.com/irs-seeks-transaction-records-of-all-coinbase-users/
https://cointelegraph.com/news/bitcoin-anonymity-over-united-states-government-seeks-identity-transaction-records-of-coinbase-users
I just read the cryptocoinsnews one, and it says the story originated at zerohedge, which is the same site that recently spread FUD that China was banning bitcoin. All the other news sites picked up on it, but it was FUD.
If the story is true zerohege has overstated and embellished it. The IRS only want details of USA customers, and are starting a court case to attempt getting permission. It might lose the court case, and court cases normally drag on for years so there will be no immediate effects.
https://www.cryptocoinsnews.com/irs-targeting-bitcoin-transaction-records-coinbase-users/
The cryptocoinsnews story gives this quote from a reddit post claiming to be by a coinbase employee called CB-Dave.
https://www.reddit.com/r/Bitcoin/comments/5dnyte/the_irs_is_seeking_the_identities_and_transaction/da6017c/
This coinbase page says it does have an employee with the reddit name CB-Dave.
https://support.coinbase.com/customer/en/portal/articles/1766604-is-coinbase-present-on-social-media-
The IRS won't be getting any transaction history quickly, and might never get any if it loses its court case.
The evil truth be that a lion chunk of pseudonews spreading across the web like a plague has the origin on zerohedge. Its run by bovarian or romanian 40 yo dude if Im not mistaken who seems to have moved to the US but apparently failed to spare a bit of his lifetime savings and buy a 10 bux SSl certificate for that site. Indeed Trustworthy source doh
The next stage of the investigation assumes someone has to contact CB-Dave guy (if he exists of course) and ask what he has to say.