See this IRS website for a CP22A notice - https://www.irs.gov/individuals/understanding-your-cp22a-notice
See this TurboTax support FAQ for a CP22A notice - https://ttlc.intuit.com/questions/3503091-i-got-a-cp22a-notice-from-the-irs
For assistance in understanding the IRS notice you received use the TurboTax Audit Support Center during business hours to speak with a support agent.
Support is open from 5am to 5pm Pacific time, Monday thru Friday
Go to this TurboTax website for the Audit Support Center - https://support.turbotax.intuit.com/irs-notice/audit-support/
See this TurboTax support FAQ for the Audit Support Guarantee - https://ttlc.intuit.com/questions/1901504-what-is-the-turbotax-audit-support-guarantee