The tax that TT shows I owe is more than the IRS schedule shows. Why is TT using a blended rate instead of the published IRS tax schedule?

It depends.  It may be that you have another tax besides the regular income tax, such as self employment tax or premature distribution penalty, or amounts due for social security and/or medicare, to name a few.  Without knowing what you have on the return or the numbers we would not be able to give clear reasons.

You can send us a “diagnostic” file that has your “numbers” but not your personal information.  If you would like to do this, here are the instructions: 

TurboTax Online:

Go to the black panel on the left side of your program and select Tax Tools. 

1. Then select Tools below Tax Tools. 
2. A window will pop up which says Tools Center.  
3. On this screen, select Share my file with Agent. 
4. You will see a message explaining what the diagnostic copy is.  Click okay through this screen and then you will get a Token number. 
5. Reply to this thread with your Token number. This will allow us to open a copy of your return without seeing any personal information.  

TurboTax CD/Download:

If you like, you can send a copy of your return that will be scrubbed to eliminate your personal data by using these steps:

1. Click on Online in the top left menu of TurboTax CD/Download for Windows
2. Select 'Send Tax File to Agent'
3. Write down or send an image of your token number then place in this issue.
4. We can then review your exact scenario for a solution.
5. Please also tell us any states included in the return. 

We will then be able to see exactly what you are seeing and we can determine what exactly is going on in your return and provide you with a resolution. 

I too am having the same struggles understanding it in the Summary pages of TT docs/pdfs. For starters the effective tax rate state 12.26% and not about of wishful thinking makes that a valid/true number. The effective tax rate should be total tax divides by taxable income. Using that formula it shows my effective tax at 21.83%. The state summary calculates correctly by the way. This error alone has cause me to second guess the whole of TurboTax. This is why I looked up the tax schedule on your site and IRS.gov. Luckily those two pages matched. If in fact I am paying for more than just taxes, ie. Social Sec, etc., should the summary not be programmed better to list out the numbers accurately? This is a huge letdown for such a pricy software package. Every year costs go up and it seams that desktop app quality is getting worse as the higher ups focus on Online versions which cost even more because of "LIVE" support.

If I were to double check the fine details on the printed forms where would I find the numbers for the Social Sec, and other line items that make the total bill?