The Berwyn Group's AddressCheck solution was recently mentioned in OneAmerica's monthly newsletter in an article on Finding Lost Participants.  As OneAmerica notes there are several simple steps to take to reduce your Pension Benefit Guaranty Corporation (PBGC) premiums by cashing out small balances.

Timely distribution of small benefit or account balance cash-outs can help reduce the instance of lost participants. Small benefit cash-out rules are governed by the plan document. The Internal Revenue Service permits a plan document to include the following mandatory cash-out rules: 

• Value of retirement benefit or account balance is $1,000 or less. If the participant does not make an election regarding distribution of his or her benefit or account balance, the benefit or account balance can be distributed in cash without the participant's consent.
• Value of retirement benefit or account balance is $1,001-$5,000. If the participant does not make an election regarding distribution of his or her benefit or account balance, the plan can transfer the funds to an IRA established for the participant.

They further mention some of the difficulties and downside to utilizing the Social Security Administration's (SSA) Letter Forwarding service: Price, Time (up to six months), and lack of follow up options (none).