An IRS CP11A Notice usually is sent due to the IRS making changes to your return because they believe there's a miscalculation involving your Earned Income Credit (EIC). This could be caused by your failure to report all of your income or claiming a dependent that you may not be eligible to claim.
The IRS notice you received explains exactly why you owe additional taxes. It also has a telephone number for you to call if you have questions or disagree with the IRS assessment. You Must contact the IRS within 60 days of the date of your notice if you disagree with the changes the IRS made.
If you need assistance with understanding the IRS notice then use the TurboTax Audit Support Center and speak with a support agent - https://support.turbotax.intuit.com/irs-notice/audit-support/
Support is open from 5am to 5pm Pacific time, Monday thru Friday (closed for Labor Day)
