That could be a scam. First---the IRS has nothing whatsoever to do with whether you paid your state tax. The IRS collects your federal tax. The IRS would not send you a letter about your state tax. Your state would deal with your state tax due. Contact your state and ask if the state sent you a letter regarding 2018.
https://ttlc.intuit.com/turbotax-support/en-us/help-article/state-taxes/contact-state-department-rev...
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
