Roughly speaking, suppose that 20% of the balance of your IRA can be attributed to non-deductible contributions, while the other 80% of your IRA is composed of deductible contributions and earnings. In that example, 20% of your withdrawal would be non-taxable, and the other 80% of your withdrawal would be taxed. (This is computed on your tax return by taking information from your prior form 8606, and adding it to the current tax tax year.) I have not tested the scenario, but I would expect that in the tax program, after you enter the 1099R for the withdrawals, TurboTax will ask you if there were any special circumstances. You can indicate that you have non-deductible contributions, and the program should go into asking you about form 8606.
Because of your age, you will also pay an additional 10% penalty for early withdrawal, assessed on the entire amount.
