If a retirement plan's trustees have changed, do we have to amend the plan document, or would a resolution suffice?

Who signs it? The old trustees and the new ones, or just the new trustees?

Does anyone have sample language?

Change of trustee usually indicates amendment of trust documents, and would require amendment of the plan document(s) only if the plan and trust are contained in the same document.

As always, read the document to verify. If a collective bargaining agreement is involved, read that also.

The language of the plan and/or trust agreement should be checked to see who has authority to appoint new trustees. Many plans provide that trustees are appointed by the Board of Directors of the employer sponsor. If an institutional trustee is being replaced, there may be a notice requirement. Notice generally can be waived, but you should document the waiver of any required notice period. A lot depends on the language of the plan and trust document. Also, the resignation or removal of the "old" trustees should be documented together with the "new" trustees' acceptance of the position of trustee. Finally, you should determine whether any ancillary steps need to be taken (e.g., changes on signature cards, notification of investment providers, fiduciary liability carriers, etc.) Although it is a little awkward, you also might want to make sure that the new trustees may serve as fiduciaries under ERISA (e.g, no felony convictions).

A less awkward way if you have individuals rather than an institution as a successor trustee is to ask the successor individual trustees to present a copy of their ERISA bond. Hopefully the bonding company will check into any felony convictions and you don't have to ask.