I suggest responding to IRS with documentation and an explanation as to why you don't think you owe IRS $319 plus interest, by March 22. If you have questions, you should call IRS, by March 22, using the contact information on your letter.

I am in similar situation.  does turbo tax help with responding to IRS?

If you purchased Audit Defense for your tax return, call Tax Resources, Inc. at (877)-829-9695, or report your notice on their web site at http://intuit.taxaudit.com/. Do not contact the IRS. Let Tax Resources contact them for you.

This is the membership email you should have gotten:  https://ttlc.intuit.com/questions/1901569-when-will-i-get-my-audit-defense-membership-kit

Also read the member agreement at this website -https://turbotax.intuit.com/corp/auditdefense.jsp

If you did not purchase Audit Defense:

TurboTax has a special phone number for help with IRS 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.

https://support.turbotax.intuit.com/irs-notice/audit-support/