The IRS deals with your federal tax --- not your state tax. So look at your letter again----was it sent to you by your state?
I RECEIVED A LETTER FROM THE IRS/STATE
TurboTax does not receive any information from the IRS or your state after your return was filed, so no one at TurboTax knows about a letter you received from the IRS or the state.
https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-audit/turbotax-audit-support/L6AcMoNFD_US_en_US?uid=m5z7by9u
https://ttlc.intuit.com/turbotax-support/en-us/help-article/internal-revenue-service/got-cp2000-notice-irs/L7Da6em2t_US_en_US?uid=m4of6ngd