A disclaimer, for an IRA, must be done by a certain date and conditions to be considered valid and remove the disclaimer as a designated beneficiary under tax law. To know if a disclaimer is valid is a legal conclusion. Since a valid disclaimer might remove the only named beneficiary, if valid, the IRA may be returned to the estate. If there is any doubt as to the timeliness of the disclaimer, a prudent executor out of abundance of caution would probably include it with probate packages to have a judicial determination of its validity.