We cannot see your tax return or access your account, so we have no way to check over your return for you. We cannot look and know if you entered some income incorrectly or did not enter all of your income. We only know what you tell us--which was that you got a "letter." If you do not understand the letter then wait for normal business hours next week and get someone to help you. Print a copy of your tax return out so that you can have it in front of you when you talk to someone. And make sure you have copies of your proof of the tax you paid--cancelled checks, your bank or credit card statement, etc. The IRS does make mistakes--maybe you will just have to provide proof that you paid.
https://www.irs.gov/individuals/understanding-your-cp504-notice
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
