I prepaid 2018 property tax in 2017 thinking to deduct more this tax year. However Turbotax is ignoring the added amount and not deduct more. What wrong ?

[smvasagam]

No matter I add the regular 2017 property tax or the total amount of 2017 and prepaid 2018 tax in primary home property tax section, turbo tax deducts only the regular 2017 property tax paid and ignores the 2018 prepaid amount. Is there a limit on how much property tax deduction needs to be for 2017. ?

[TaxGuyBill]

Are you saying the amount on Schedule A (Itemized Deductions) shows the wrong amount, or are you saying your refund does not change?

Look at your Form 1040.  Is there a number on Line 45?

[smvasagam]

Turbotax online shows that it used what ever property tax amount I enter (either 2017 only or 2017+2018) property tax for deductions. However tax I owe does not change. I mean it look like it uses only 2017 property tax paid and ignores the 2018 prepayment. Forms are visible only in Downloaded version.

[TaxGuyBill]

You can still look at your tax forms.  You can either pay now to see them, or if you just want to see the 1040, you can "preview" it:
<a rel="nofollow" target="_blank" href="https://ttlc.intuit.com/questions/1901539-how-do-i-preview-my-turbotax-online-return-before-filing">...>

[smvasagam]

After I pay, it allows me to see. Yes my scheduled A reflects the changed itemized deduction when I enter a hight amount. However it does not reflect in tax I owe. My taxes owe does not change , no matter my scheduled A total increase or decrease.

[TaxGuyBill]

As I asked before, look at your Form 1040.  Is there a number on Line 45?

[smvasagam]

Yes 1040 line 45 does get impacted with just 2017 property tax vs (2017+2018) property tax. However there is no change in tax I owe. Not sure why.

[smvasagam]

So do I have a solution for this ? I mean am I automatically subjected to AMT , as a result I won't get any benefit for prepayment of 2018 taxes ? . Do I have any alternative. ?

[TaxGuyBill]

Nope, no alternatives. Sorry, that is how the tax laws work.

[TaxGuyBill]

Line 45 is Alternative Minimum Tax (AMT).  Real Estate taxes are not a deduction for purposes of Alternative Minimum Tax.

That effectively means that if you are subject to AMT, adding more real estate taxes will not increase your refund.