Tax entered on Form 1040 line 11a does not match IRS Tax Table amount for Taxable Income on line 10.

TurboTax entered Taxable Income on Form 1040 line 10 as $70,930 and line 11a Tax as $7,944.  But IRS Tax Tables for 2018 show corresponding tax for Married filing jointly as $8,130.  Why the difference?