A distribution made to the beneficiary of an IRA will have code 4 in box 7 and will have the IRA/SEP/SIMPLE box marked. If the Form 1099-R provided by the payer does not agree with this, the distribution is not from an inherited IRA. In that case, what is the code in box 7 and is the IRA/SEP/SIMPLE box marked?
For a distribution from an inherited IRA, TurboTax asks you to explicitly enter the amount that is taxable because less than the full amount would be taxable if the decedent had basis in nondeductible traditional IRA contributions. The result you see suggests that you entered $10,000 as the taxable amount when TurboTax asked for this. TurboTax then uses this entry to replace the amount you originally entered into box 2a of TurboTax's 1099R form.
Either edit this form 1099-R and correct the box 2a entry or delete and reenter this Form 1099-R, paying close attention to what TurboTax is asking for.
