1099-r taxable amount not determined

[forbeste]

I cashed out a Life Insurance policy that I had held for about 16 years. During the time the policy was in force I did a 1035(a) exchange to a different company. The previous carrier did not transmit the cost basis to my new carrier. The 1099-R I received from the new carrier has the taxable amount blank and Taxable amount not determined checked. When I enter this info into TurboTax, the entire distribution is taxed. This can't be correct. What do I do? The followup questions only asked about pension plans and hurricane relief.

The entire amount should not be taxable since I have made nearly $35k in after-tax premium payments over the life time of the policy.

[JohnB5677]

If the distribution is from the cashing out of an insurance policy, and Box 2a is blank, the entire amount of Box 1 is taxable unless you can calculate the taxable amount and enter it in Box 2a. Don't enter an amount unless you know the taxable portion of your distribution.  That would be the total amount of Box 1 less the insurance payments you made over the years.

See instructions for Box 2a in 1099-R Instructions