Unless the distribution or payment no longer can be questioned because of adjudication, estoppel, or limitation, a distributee of property improperly distributed or paid, or a claimant who was improperly paid, is liable to return the property improperly received and its income since distribution if he has the property. If he does not have the property, then he is liable to return the value as of the date of disposition of the property improperly received and its income and gain received by him.