I just received two calls within two hours from this number. The first time, I picked up the phone. It was an automated call with a voice synthesizer saying it was a final notice from the IRS. Obviously it was a scam, so I hung up. If the IRS had any issue with me, they would contact me with an official letter in the mail. They would not be calling me from Washington state. The caller ID just said "Washington call." I think they expect most people to perceive that as "Washington, DC" and not recognize that the 206 area code is the Seattle, Washington area.
The odd thing is that I have an unpublished number and am on the Do Not Call list. I still get scam calls like this on a regular basis.
I have received 3 calls from this number this morning claiming to be the IRS. I called them back, told them I was reporting the scam and they said they were going to call me 10 times more!