Iowa Code § 562.10: Rental value.

The holder of the interest succeeding a life estate who is required by section 562.8 or 562.9 to continue a tenancy shall be entitled to a rental amount equal to the prevailing fair market rental amount in the area. If the parties cannot agree on a rental amount, either party may petition the district court for a declaratory judgment setting the rental amount. The costs of the action shall be divided equally between the parties.