Minn. Stat. § 90.193

The commissioner may, in the case of an exceptional circumstance beyond the control of the timber permit holder which makes it unreasonable, impractical, and not feasible to complete cutting and removal under the permit within the time allowed, grant one regular extension for one year. A written request for the regular extension must be received by the commissioner before the permit expires. The request must state the reason the extension is necessary and be signed by the permit holder. An interest rate of five percent may be charged for the period of extension.