Sorry they don't work that way. What does the letter say you left off or reported wrong? There should be a CP or LTR # up in the corner. Here's some common things.
I would check over your return and see if you can see anything wrong especially in the payments section 1040 lines 64 to 73 (1040A lines 40-41). Make sure you agree with all the amounts listed. Like is the difference the same or close to the refund you got last year? Maybe you put down that you applied last year's refund to this year? Or you put down you made a payment with an extension or paid an estimated payment that you didn't make?
A common error is showing an estimated payment 1040 line 65 (1040A line 41) you didn't make or payment with an extension (line 70) you didn't send in. Sometimes people start an extension form on purpose or accidentally and an amount gets entered for a tax due to send in with the extension.
Or you claimed Excess Social Security paid on line 71. That happens when you are married and enter both spouse's W2s under the same name.
Or if you got any 1099Misc forms you didn't report it as self employment income on 1040 line 12 and pay the SE tax on it. It might have showed up on line 21 for Other Income instead of line 12 business income.
Or the IRS changed your income. A common thing they change is the taxable amount of any 1099R for pension, 401K or IRA distributions or conversions. And if you get Social Security and they increase some income it will make more of your SS taxable. Oh, and make sure your 1099R is showing up on the right line. If it is on the wrong line the IRS will miss it and say you didn't report it.
