Mich. Comp. Laws § 700.2903: Contents; signature.

Sec. 2903.

A disclaimer is not valid unless it complies with all of the following:

Is in writing.

Declares the disclaimer.

Describes the disclaimed interest.

Is signed by the disclaimant.

Is delivered as provided in sections 2904, 2905, and 2906.

If a disclaimable interest is disclaimed by a fiduciary on behalf of the person to whom the disclaimable interest devolves, the disclaimer must be signed by all incumbent fiduciaries. Unless the governing instrument requires otherwise, a disclaimer of a disclaimable interest by a trustee may be signed by less than all incumbent trustees. A disclaimer of a fiduciary power by a fiduciary may be signed by less than all incumbent fiduciaries.