I've just spotted something interesting on the HMRC which I don't think used to be there.
edyourself.org/articles/benefits.php#qualifyp
"Qualifying Young Person" Age 16-20
As stated on the Directgov web page on Child Benefit after 16:
"The Child Benefit Office can carry on paying Child Benefit up until the age of 20 if the qualifying young person is in relevant education or training.
HMRC web page on reporting changes after your child is 16
www.hmrc.gov.uk/childbenefit/keep-up-to-date/changes-to-report/what-to-report.htm
HMRC lists the changes which must be reported, including when the child "stays on at school or college after the date you told the Child Benefit Office they would leave" and "starts being educated at home and is 16 or over".
Logically I can't see why you would need to tell the CB office if a child started to be educated at home, unless you could claim for the child, since you have to tell the office anyway if a child leaves college.
It has been said that home ed needs to have started before the age of 16, in order for the young person to qualify, but I disagree.
It might seem an odd thing to post on a home ed list, but sometimes I'm asked by a parent who has a child in school and a child out of school, or where a child was home ed, starts college, and then returns to home ed.
edyourself.org/articles/claimbenefitspost16s.php
Fiona