My son is graduating fron8th grade at a charter and will go to 9th grade in home district. 
is the new school obligated to follow his  IEP? What are its legal obligations? What usually happens?

we have a number of accommodations to help him self regulate and support him with executive function

i know this switch will be overwhelming and am worried it will lead to behavior problems

It is my understanding that charter schools are considered public schools for purposes of an IEP because they are publicly funded.  If so, the obligations of the public high school you are transferring to would be the same as if he were transferring from another public school.  Those obligations are to either accept or reject the previous school's evaluation and IEP.  If they accept, they must implement.  If they reject, they must keep the "old" IEP in place until they conduct their own evaluation.

I would suggest reaching out to the new school NOW to discuss transition and what documentation they will need.  I would also ask for a meeting with the special education team to discuss your concerns regarding the transition.

Finally, since all states are a little different, I would advise reaching out to your state department of education (special education division) and ask them what the procedures are for transferring from a charter school to a public school.

In the US, all charters are public and just as beholden to the laws. The new school will likely review the IEP within the first month or so of receiving it to make sure all is in order. Until then, they will follow it.

8 hours ago, Carolyn Rowlett said:

It is my understanding that charter schools are considered public schools for purposes of an IEP because they are publicly funded.  If so, the obligations of the public high school you are transferring to would be the same as if he were transferring from another public school.  Those obligations are to either accept or reject the previous school's evaluation and IEP.  If they accept, they must implement.  If they reject, they must keep the "old" IEP in place until they conduct their own evaluation.

I would suggest reaching out to the new school NOW to discuss transition and what documentation they will need.  I would also ask for a meeting with the special education team to discuss your concerns regarding the transition.

Finally, since all states are a little different, I would advise reaching out to your state department of education (special education division) and ask them what the procedures are for transferring from a charter school to a public school.

We are in Pennsylvania and our school said they would ask the district to come to a transitional IEP meeting. I don’t know what they will say and that is in May.

so it sounds like - worst case scenario they will reevaluate and he is back at square one. He has an FBA, too. 

An IEP from a public charter schools in PA would need to be followed by the public school when your child moves into a district school.  As with any 'move', the new school will look to see if additional evals are needed.  He would not be at square one.  They have to follow the IEP for a month before they decide on what changes are needed.  Did the school develop a PBSP after doing the FBA?  An FBA is an evaluation to see if a student needs a PBSP.  The PBSP is often part of the IEP & would need to be followed just like the IEP would need to be followed.

Transition is a different issue.  In PA, transition age is 14 so the school is obligated to look at 'life after HS' when a student turns 14.  Traditional public schools are more likely to use the IUs to provide transition services than charter schools.  His current school should do any evaluations related to transition so they can be made part of his transitional IEP.

Just for clarification purposes, when I used the word "transition" above, I was referring to the transition from the charter school to a new school - not transitioning from high school to post-graduate life.  As JSD24 pointed out, that is a separate issue that the new school will have to look at when the student turns 14.

I wouldn't use the word "transition" I would say "transferring." As transition is typically applied to post-secondary skills. If a student is transferring from one school district to another within the same state the school should hold a Transfer IEP meeting within 30 days and offer comparable  services until they hold the meeting and the team determine the student needs different services (you are a member of that team). At least that is the way it works in the state of Missouri. Not all services will be the same from one school to the next due to the school's resources. Still the school should be offering to do what is best for the student.