At 11... I did help. Here, there is no IEP unless the SCHOOL believes the student needs accommodations, and they thought it was all attitude. He had a good teacher, though, so I stepped on toes and forced her to allow the WHOLE project to be done at home. Then... I scribed and helped edit, suggested layouts and other such things - and got her approval on each section as we went, while including a description of the accommodations applied. Voila! This teacher, and the next one, started providing those accommodations, and by the second school year, we had an IEP.
If I had let him get a zero? School would still have claimed it was becaue he didn't want to - not because he couldn't do the work in the ways the school was demanding.
You really have to know your local system and how it works, and what you are trying to accomplish by "helping". The goal is to get the student working as independently as possible, and definitely independent of "home" help... you do whatever you have to do to get there.