Answer: Yes, it is true. There are no stay-put rights to a 45 day placement. Unlike what the name implies, 45 day placements are evaluations, not placements for IEP purposes. Your child's stay-put placement is the last placement you and the district both agreed to.
If you have more questions about special education law and need help advocating for the placement your child needs, contact the Boston area Law Office of Lillian E. Wong.