Hi. My name is*****'m looking at your question now and will post my answer or ask for more information here in a short while.
Is the policy one that was tied to your mortgage whereby you paid monthly premiums? How long were premiums paid for?
The assignment makes absolutely no difference. As you have paid the premiums for as long as you have, there will be no tax to pay if you surrender the policy or have already done so. See page 3 here.
I hope this heslp but let me know if you have any further questions.
Your message that you had surrendered the policy in 2015 did not post before I completed and posted my answer.
Unless you received a chargeable event certificate from the life company when you surrendered the policy, there will be no taxable gain. Gains on qualifying policies which is what yours was are not normally taxable even on divorce. Gains on non-qualifying policies are. The notes on page 5 refer to them.