Tax due per TurboTax vs IRS tax schedules

THIS QUESTION IS FOR THE TURBOTAX PROFESSIONALS, NOT FELLOW USERS

 

Questions re TurboTax calculations on our program: TurboTax Home and Business

 

Our total income is shown as $142,610.

Our Federal Deductions are shown as $62,865.

Our Taxable Income is shown as $67,120.

Our Federal Taxes owed is shown as $18,798.

 

18,798 divided by 67,120 shows our tax rate to be 28%.

 

taxfoundation.org (and IRS.gov) lists federal tax rates for joint filers like us as:

10% on first 19,750 = 1,975.

12% on 19,751 to 80,250 (to 67,120 for us)  = 12% of 47,369 = $5,684.28

 

       1,975.00

+     5,684.28

$     7,659.28

 

NOT $18,798 !!

 

HOW DOES TURBOTAX EXPLAIN THIS DISCREPANCY ?!?