I receieved a CP501 and a CP14. I filed my taxes correctly (as far as I'm aware) using TurboTax. What's going on here?

[Critter]

Both  notices say you have a balance due with the IRS ... did you not pay your federal balance due on the return you filed ?  

https://www.irs.gov/individuals/understanding-your-cp501-notice

https://www.irs.gov/individuals/understanding-your-cp14-notice

[brian-p-poole]

I paid everything turbotax told me to. They're claiming I paid late. I don't see how?

[Critter]

If you paid the balance due after 4/18/17 then you paid late.

[brian-p-poole]

I paid 4/15/17, with an extension which was completed before 10/15. The balance is minimal, just really annoying... I wish TurboTax would be smart enough to know this. Seems it's only good for standard taxes.

[Critter]

Sorry but the program only computes an estimate of the underpayment penalty but the IRS is in charge of the failure to file  penalty, the failure to pay penalty, the final underpayment penalty & interest for which they bill you after you file.

[brian-p-poole]

The basic gist seems to be: I ended up owing a little more by the time I paid the extension. There was no mention of the penalty while filing. The IRS's letters are because I did not pay that penalty. Personally, I think TurboTax should have calculated that or at least made mention of it so I could avoid the other charges added on afterwards.

[Critter]

It would if it could but it can't ... again only the IRS has that ability.  As to warning you about penalties to come you may have a point ... but the program does try to educate you in the estimated payment section by producing estimates for the following year based on this year's tax liability.  But in the end it is just a program and not a live preparer ... if you were at my desk I would have explained what to expect.