Yes, TurboTax does support the above-the-line $300 cash donation deduction.

For 2020, you are allowed to deduct up to $300 ($150 if Married filing Separately) of cash donations to 501(c)3 organizations even if you do not itemize your deductions.

In order to take this above-the-line deduction, enter your donation(s) under Deductions & Credits > Charitable Donations > Donations to Charities in 2020.  The deduction will be added above-the-line by TurboTax after you have completed the  Wrap up tax breaks interview in TurboTax if you take the Standard deduction.

On your form 1040, this deduction appears on line 10b - Charitable contributions if you take the standard deduction.

To check that the cash donations have been transferred to line 10b of form 1040 and deducted from your income, please preview your form 1040 by following these steps:

1. In TurboTax, open your return
2. In the left-hand column, locate Tax Tools, click on the drop-down arrow then click on Tools
3. On the Tools Center page, click on View Tax Summary
4. In the left-hand column, click on Preview my 1040
5. Your form 1040 will display.
6. Scroll down to line 10b - Charitable contributions if you take the standard deduction and you should see the amount of this deduction on this line.

I am using Turbotax Home & business on a Mac.  I entered the charitable contributions as mandated.  The $300 deduction is not reflected on the 1040 line 10.  There is a bug.  Taxpayer does not itemize.  What is wrong?

There are two steps in entering the line 10b above the line deduction.

The first is to enter the contribution in the charitable contributions section (it must be as CASH).

The second step, which is not obvious to taxpayers, is that during the Final Review when TurboTax knows that (1) you have made one or more cash contributions, and (2) you are taking the Standard Deduction, then TurboTax will ask you the amount to put on line 10b.

Only after this is done will the amount appear on 10b.