HELP: I can't get my spreadsheet calculated taxes to match TurboTax

[roscoedillon]

I have a spreadsheet that I use to calculate my taxes using the Married Filing Jointly brackets.  I have verified in the past that my math is correct (I'm pretty good with spreadsheets).

However, I'm ready to file my taxes and ran a cross check only to find my spreadsheet numbers don't match TurboTax 1040 Line 16 ("Tax").  Of course I assume TurboTax is correct, but I want to predict next years taxes so I need to get my spreadsheet is working correctly.  First, I assume that 1040 Line 15 ("taxable income") is the number I push into the tax bracket calculations.  Given that, is there a website anywhere that will show the tax calculations for a given taxable income input so I can try to figure out what's going on?  

Thanks!

[RobertB4444]

Your final tax rate can be much more complicated than what is on the tax tables.  The tax tables assume that you have no long term capital gains or pass through income any other income taxed at a different rate.  

TurboTax provides a refund calculator here although the math is not out there for you to see and I assume the formula is what you want in order to program your spread sheet.  

If you break out each type of your income separately and then calculate the tax rate for each type of income at it's proper rate and total it in the cell that has what you will owe that should get you where you're going.

@roscoedillon 

[roscoedillon]

Forgot about capital gains...thanks, that's it!