Did TT underpay my taxes?

[123champ]

When I filed my taxes in April I paid exactly the tax TT said I owed. Now I got an IRS notice CP23 saying I underpaid by a couple of hundred bucks.

Puzzled, I opened the pdf copy of my return saved in April and verified that I had paid exactly what TT told me to then.

Next I opened the TT desktop app -- it went through a series of updates that it usually does -- and went to Personal >> Federal Review >> "Federal Taxes you owe". The amount TT shows there now is higher, and in line with the IRS notice!

What gives? Why the discrepancy between the pdf I saved in April when filing my taxes, and what TT shows now in June? I haven't opened the app again in the past two months, and haven't entered any new data. Did the software updates TT keeps doing force any adjustments?

[VolvoGirl]

You can compare your new data file with your original pdf.  You can open the Forms and compare the 1040, etc.  What is different?  

[123champ]

Thanks. I compared the two forms and noticed that the QBI deduction on line 13 of form 1040 reduced. Tracing it to form 8995A, I see that TT earlier showed an amount on line 2 as Qualified Business Income related to a rental property, whereas now it shows a zero value.

Not sure why. Also, I see now that the difference doesn't quite add up to what IRS says I owe.

There's probably an explanation for all of this, but at this time, I guess it's best to just pay up.

Thanks VolvoGirl for the help!