Notice of Deficiency CP3219A for 2018

[6picas]

I received a CP3219A (Notice of Deficiency - Proposed Tax Increase. I used TurboTax Deluxe that year. I don't know if I should agree or disagree with this notice. I now owe them an additional $3,715. Do I agree or disagree? What is TurboTax's responsibility here? How did this error occur if I filed everything correctly and it was accepted in 2018? 

[JotikaT2]

Please see the attached link. 

If you purchased any of the options when you prepared your 2018 tax return, you may have help available to assist you with your notice.

Responding to IRS notices

TurboTax prepares your return based upon the information you enter into the program.  Be sure you have your source documents to support you should you choose to disagree with their notice.