Calculation of Social Security earnings

[Dan93]

TurboTax correctly placed my $300.00 Charitable Contribution on line 10b of my 1040-SR return reducing my adjusted gross income; however, it also placed the same amount on my Social Security Benefits Worksheet on line 6 effectively reducing my Taxable Social Security benefit noted on line 6b of my 1040-SR by $255.00 which I feel is "double dipping" the contribution for tax purposes.  Any reason the $300 cash contribution would also reduce my taxable social  security earning amount or is this an issue with the TT program?

[MaryK4]

For 2020 this is an "above the line" deduction which means it is used in the calculation to determine AGI.  The calculation of taxable Social Security is based on Modified Adjusted Gross Income.  Since 2020 non-itemized charity is above the line it will impact MAGI which may have an impact on taxable SS.

Subject to change at any moment, but for now you can look at the draft worksheet on page 30 (pdf page 31) of the draft 1040 instructions: https://www.irs.gov/pub/irs-dft/i1040gi--dft.pdf#page=31