Similar thing happened to me, but with a much happier outcome. I lived in Iowa, moved to Colorado for a few years, and now I'm back in Iowa. I received a letter that I owed estimated taxes plus interest and penalties and... Ignored it. Then, 6 months later, I got a bill with the email address of the Iowa IRS agent. One friendly email and four days later, her response was: Thank you for your response to the Department…
I'm not sure how I was able to escape California without dealing with this, but that was some years ago...