My line10 income was $100,618 (filing jointly) using the $100K IRS formula for line 11a, it's $14,015. TurboTax put 13,250. Any idea why or do I have to do an amendment?

[VolvoGirl]

It depends on what kind of income you have, if you have capital gains or qualified dividends the tax on line 11 is not taken from the tax table but is calculated separately from schedule D.  The tax will be calculated on the Qualified Dividends and Capital Gain Tax Worksheet.  It does not get filed with your return.  In the online version you need to save your return as a pdf file and include all worksheets to see it.  

For the Desktop version you can switch to Forms Mode and open the worksheet to see it.  Click Forms in the upper right (upper left for Mac) and look through the list and open the Qualified Dividends and Capital Gain Tax Worksheet.

You can probably tell because the tax on 1040 line 44 will be less than the Tax Table
https://ttlc.intuit.com/replies/3300459

[Hal_Al]

 The  "Qualified Dividends and Capital Gain Tax Worksheet" is used most often. But, For some people, TurboTax (TT) will use the "Schedule D worksheet", instead of the  "Qualified Dividends and Capital Gain Tax Worksheet".