Caller ID said this was from a "cell phone" with a Washington DC area code. But I'm sure it could be a spoofed number coming from anywhere ...

A woman with a foreign accent and far from perfect English left a message saying that she was from the IRS and my "tax case file was about to expire in 24 hours" and then I would be taken into custody "by the cops".  Unless I called them back, legal action would be taken against me. Ended with a weirdly upbeat "Thank you, and have a great day... Goodbye!" :-0 Why thank you, evil lady scammer - so polite of you!  You have a super great fabulous day, too!

Reporting this scammer to the Treasury Inspector General for Tax Administration (TIGTA) on their webpage:  "IRS Impersonation Scam Reporting".