Iowa Code § 537.3618: Default.

An agreement of the parties to a consumer rental purchase agreement with respect to default on the part of the lessee is enforceable only to the extent that one of the following apply:

1. The lessee both fails to renew an agreement and also fails to return the rented property or make arrangements for its return as provided by the agreement.

2. The prospect of payment, performance, or return of the property is materially impaired due to a breach of the consumer rental purchase agreement; the burden of establishing the prospect of material impairment is on the lessor.