What is an acceptable zip code for Principal Life Insurance in Des Moines, IA? None of the ones listed for Des Moines works.

TurboTax can claim there is a "zip code" error, even if it's actually something else wrong with the address.  So the zip code may not be the issue.

First, be sure you are using the correct state abbreviation.  Iowa is IA, but ID, IN, or IL can easily be mistakenly selected in a dropdown menu if the mouse accidentally rolls.

Use the USPS lookup tool to get the official address styling and zip code:

https://tools.usps.com/zip-code-lookup.htm

If the street address has punctuation, try using no punctuation. e.g.,  123 N St Marys Ave instead of 123 N. St. Mary's Ave.

ADDENDUM:

You haven't said what form or topic is giving you the address problem and whether the form was imported or entered manually. 

In addition to the info I mentioned above, if you have been trying all sorts of permutations to get it to work, and it's still not successful, I'd delete the form and enter it manually from scratch to see if that resets something.   

Also, if you are trying to correct it in some "Fix It" error-check box, try navigating back to the original topic and correct it in the interview instead of that popup, or delete and re-enter as mentioned above.

The form that you received from Principal Life Insurance has their address on it, including the Zip code. That is almost certainly the correct Zip code. You should not be searching a list of Des Moines zip codes.