Excess Real estate taxes for home office calculation works incorrectly

[mbk1]

Turbotax desktop seems to be calculation excess real estate taxes completely wrong.  I have combined real estate and state property and income taxes well over the $10,000 limit.  I believe that I am entitled to deduct excess real estate taxes as line 17(a) on form 8829 as an additional home office deduction.  IRS instructions to form 8829 seem to explain how to do this, https://www.irs.gov/pub/irs-prior/i8829--2019.pdf  But turbotax inserts a zero (or leaves a blank) where I think I should have a significant deduction (on line 17(a)).  There are instructions for line 17(a) embebed in the TT form (accesible by right clicking) which seem to suggest how to do a manual calculation for this entry.  But they are confusing and see inconsistent with the IRS instructions.  And why isn't this dealt with in the interview process?  Am I missing something?  Should I just follow the IRS instructions (which are themselves not the clearest)?  My situation cannot be all that unusual, not sure why TT does not do this.  

[Mike9241]

here's how line 17 is computed from 8829 instructions

Line 11 Worksheet
1. Enter your state and local income taxes (or, if you elect on Schedule A, your state and local general sales
taxes) that are personal expenses ......... 
2. Enter all the state and local real estate taxes you paid on the home in which you conducted business . . ....
3. Enter any other state and local real estates taxes you paid that are a personal expense and not included in
line 2 ..........................
4. Enter your state and local personal property taxes that are a personal expense ............... 
5. Add lines 1 through 4 ................ 
6. Multiply line 2 by the percentage on Form 8829, line 7 .........................
7. Subtract line 6 from line 5 .............. 
8. Subtract line 7 from $10,000 ($5,000 if married filing separately). If zero or less, enter -0- .........
9. Real estate taxes reported on line 11. Enter the smaller of line 6 or line 8 here and in column (a) of
Form 8829, line 11 .................. 
10. Excess real estate taxes reported on line 17. Subtract line 9 from line 6 .............. 

you may find that line 10 is zero since if your taxes go way over $10K.  line 6 and 9 will be the same resulting in line 10 be zero and thus line 17 being zero 

[apowers00]

I am having the same problem as the original poster. I am not sure if he figured out what to do. But I figured out my mistake. For line 10, I was subtracting line 9 from line 2 instead of from line 6. Here are my numbers for the line 11 worksheet. I might be misunderstanding what is supposed to go into lines 1 and 2 of the worksheet.