Same as many above-- a gentle man with excellent English and an Indian accent told me I have a US Treasury action against me (a highly confidential matter. Confidential from me, even!), and that I needed to call Jason Brown immediately (323-786-6595 x 226). When I didn't call Jason Brown immediately (2-3 minutes), he called me again several times again.
Report the Calls to the real IRS here:
•report the incident to the Treasury Inspector General for Tax Administration at 800-366-4484.
•You can also file a complaint with the Federal Trade Commission at FTC.gov. Add "IRS Telephone Scam" to the comments in your complaint.
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Do consider maybe getting a call blocking device or phone.. You can google them and many are around $60.00 or so.