Other than the IRS letter forwarding service, what services have you used for attempting to locate lost participants? Were they easy to use? Were they expensive?

I have used a small company who specializes in locating missing participants.

They have a few different levels of service. They understand the specific issues around the qualified plan business.

It has been useful. As a referral they provided me with contact of a relatively large employer with thousands of missing participants. That employer was pleased with how they have been able to cut down on their missing participants and thus reduce administrative, ... costs.

There is also more of a self service search solution that has been helpful as well. That is more of a service when you have a small number (1 or 2) searches needed. You pay as you use the on-line service. You get a short history of the known addresses based upon SSN input. It has also been helpful.

As long as the person has a listed phone number and hasn't moved out of state, some online phone directories can be useful as a first step. We would use anywho.com (which is an AT&T product) before trying other resources. It was most helpful a) when the person had merely moved across town or to a nearby town (google maps was handy for looking up unknown towns) and b) when the person had a reasonably unique name (e.g., not John Smith).

We apparently use Accurint. I only know of it indirectly, as I don't use it, but what I've heard is good. Apparently pretty easy to use, price ok, etc. -

I did hear one comment that they (they meaning our people, not Accurint) "batch" the inquiries - it takes a while to log in to the system and get ready to go, but then each inquiry is generally pretty quick.