The letter
The legal trigger is a written request to your local council's SEN team. Address it to the SEN team (not to the school), say the words “I am requesting an EHC needs assessment for my child under section 36(1) of the Children and Families Act 2014”, and include your child's name, date of birth, and school. IPSEA publishes a free model letter you can adapt; their version is the most tightly written one in circulation and is accepted by every English local authority.
You can send the letter by email. The 20-week clock starts the day the council receives it, not the day they reply to it, so keep a copy of the sent email with its timestamp.
The two statutory windows
The council has 6 weeks from receiving your request to decide whether to carry out an EHC needs assessment. If they say yes, they have 20 weeks from your original request to issue a final EHCP (assuming one is needed at the end of the assessment). The 20-week total includes the initial 6-week decision, the assessment itself, the draft plan, and the final plan. The deadlines come from paragraphs 9.41 and 9.42 of the SEND Code of Practice 2015 and from Regulation 13 of the SEND Regulations 2014.
In practice many councils miss the 20-week deadline; you can read about real-world wait times in the sibling answer “How long does an EHCP take to get?”. Missing the deadline doesn't give the council a defence; it's still a breach of the law and a ground for complaint.
What happens if they refuse to assess
The council can refuse to carry out the assessment at the 6-week point. If they do, they must give reasons in writing, and you have the right to appeal that refusal to the SEND Tribunal within 2 months. Most refusal-to-assess appeals succeed for parents. See the sibling answer “What do I do if my EHCP application is refused?” for the appeal route.
What happens if they agree
The council will arrange the assessment over the following weeks: typically an Educational Psychologist (EP) report, a letter from the school's SENDCO (the teacher in charge of special needs), and reports from any clinicians already involved (paediatrician, Speech and Language Therapist, Occupational Therapist). You'll be asked for a parental contribution; write it as if no-one reading it knows your child. Specifics work; generalities don't.
After the assessment, the council decides whether to issue an EHCP or not. If they decide yes, you'll receive a draft plan, then a final plan, both within the 20-week window.
Where the law comes from
Related
This page is general information, not clinical or legal advice.