Normally companies will not give tax advice, as they are not experts and don't want to get sued if it is incorrect. So you will probably not get anywhere with them.
I can tell what I think is going on. This, as you said, is an old Pension. There was what is called a 3-year rule. What this did, say you put in $25,000 pretax money into the Pension while working.
Then when you retired, the first 3 years you were able to collect $9,000 a year or $27,000.
Under the 3 year rule, the first $25,000 (or recovery of your pension money) is tax-free.
In this example, the $2,000 is taxed and all remaining money is taxed as income also.
I think this is your situation.
If not, unfortunately, you would have to get some returns for when he first retired and see how it was handled to be able to show the IRS that this should not be taxed.
Hope this helps shed some light on this matter.
