It's The Same The Whole World Over...
I live in Canada; I work in the US.
I recently received a VERY aggressive letter from the US IRS that I hadn't filed my tax return... which I had. On calling the IRS, the lady said "Yes, it's posted but not reviewed. They didn't check on the system", or words to that effect.
Anonymous because I've had many, many issues with the IRS, and it's not wise to pi$$ them off.