I checked into this with the department of revenue. The software side basically said check the box for inter vivos trust instead, and their system will not look for the decedent's social security number or the court information. I think the attitude at least of the software guy is that the testamentary box is for court reported trusts. One of the policy guys, who clearly knew nothing about it, basically said "file on paper." I was successful in electronically filing by changing from 'tentamentary' to 'inter vivos' without dredging up the SSN of a decedent from 30 years ago. So, if you want to file an Iowa 1041 electronically with Proseries, wink at whether it is testamentary, mark the inter vivos box, and send it off.