You should also provide a copy of the last will that designates you as the executor and beneficiary of the estates.  It is this document which grants you the right to inherit.  If the pension administrator is still nervous about whether or not you are the final heir, you may need to file a simple probate and have a judge declare you as the sole heir, put it in a court order, and then send it to the pension administrators.  However, before you go throug all of these hoops, consult with a probate attorney and let them review what information you have regarding the pension plan.  Some pensions only permit spouses and minor children to be disignated as beneficiaries.  If this is that type of plan, then you don't need to go through the probate process, only to be denied benefits because of a plan administration requirement.