If you place your child in private school at your own expense (including a religious school) your child still has the right to receive special education services from the school district in which you reside.
While federal law requires only "equitable services" for children in this situation, Massachusetts sets a higher standard. Massachusetts requires that special education provided by the school district to a private school student shall be comparable in quality, scope and opportunity for participation to that provided to public school students with needs of equal importance.
If you believe your school district is not proposing adequate services for your child because your child is in private school contact a Massachusetts special education attorney.