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. If you want to tell us what the letter says --without giving use your personal information please -- we may be able to help.
TurboTax has a special phone number for help with IRS/state tax letters, which will be easier than going through regular Customer Support. At the page below, click on the blue button that says "Get Help from TurboTax Support". Then it will ask you what tax year is your letter. Then it will ask you what the letter concerns. Then it will show you the phone number during posted business hours.
Maybe its due to thisTTX software error?
IF you filed before 1 Feb...that could be the issue.
There's a telephone number ion the FAQ for help, but don't call after 5PM PAcific (I don't think those hours are correct)