The IRS questioned the deduction the software took on my Social Security for 2017. why?

[havenonfedhill]

My SSA benefits totaled $39,671. The Turbo tax software on line 15b gave the taxable amount as $13,749.00. 

The IRS is claiming that I underreported this income. They claim the income should be $33720.00.

Why?

[VolvoGirl]

What year?  SS is on line 5 and in 2017 and earlier it's on line 20.
That's because they changed some OTHER income on your return.  They either said you left out some income or changed the taxable amount of any 1099R for IRA or 401K on line 4b or for 2017 lines 15&16 .  They increased your other income which is making more of your SS taxable.  

[SweetieJean]

Did you forget to claim (or mistype) any other income of any type: 1099-INT, 1099-DIV, 1099-B, 1099-G, etc.?

[Anonymous · Accepted solution]

most likely the IRS is claiming you underreported your taxable IRA distributions  line 15b. Increasing line 15b can make more of your social security benefits taxable.  It won't if your already being taxed on 85% of those benefits (line 20b is 85% of line 20a)

carefully check you TT entries for IRA distributions against the 1099-R's you got and make sure you have them all and that you enter them all correctly.  

you may want to go to the IRS website click on get your tax record and review the transcript for the year in question.  it should detail all the IRA distributions reported to them.  It's always possible you never got one.