Iowa Code § 633.53

In all accountings filed by fiduciaries, vouchers or receipts for all disbursements shall be filed or submitted by the fiduciary upon written request of any interested party, or upon order of court. After an order, or decree, has been entered approving such accounting, any vouchers or receipts which have been filed may be withdrawn under order of the court. Vouchers or receipts not filed, or which have been withdrawn, shall be preserved by the fiduciary until the accounting of such fiduciary becomes final.