Box 5 is for reporting the amount of the participant's investment in the plan that is included in the distribution, recovery of basis. It is not for reporting amounts paid out of the plan for health insurance coverage, even though some payers inappropriately use it for that.
An amount paid directly from the plan for up to $3,000 of a PSO's health insurance can be excluded from income, with the exclusion amount entered by the user into TurboTax in the follow-up to entering the details of the Form 1099-R, in which case TurboTax will exclude the amount from the amount otherwise shown in box 4d of Form 1099-R and will include the notation PSO next to line 4d. As macuser_22 said, if any portion doesn't qualify for the PSO exemption, that would generally need to be reported as a Schedule A medical deduction or, if one is self-employed and the payment qualifies, perhaps as a self-employed health insurance deduction.
