I realise this isn't a popular view in this day and age, and I expect I will be flamed, but I think a 6 year old who slaps mum round the face (autistic or not) needs to be punished immediately, so they know not to do it again (to mum, or anyone else). I would never ever hit a child, but I do think the punishment needs to be a) instant and b) something that the kid really really doesn't like, so that they make the link. If you don't show zero tolerance for aggression when they are 6, you are in trouble when they are 15. My autistic boy was aggressive at 3, we used to wash his hair to punish him. That won't work for everyone, you need to find what works for you. The trouble is that the "establishment" will just give you things like naughty step or time out, which are uniquely unsuitable for autistic kids as they WANT time out on their own! I think all children should be taught that there's zero tolerance on violence, and if they are significantly non-verbal, as my boy was at that time, you are limited in what you can do as you can't talk to them. Therefore negotiation, as I would use with my NF child , is a non-starter ("if you do that, you will lose computer time/TV time/playdates etc). So you have to SHOW, not tell. Sorry if this is unpopular view, am really trying to help as I know how awful this stage feels. If my boy were still hitting and headbutting today, I would be getting seriously injured, plus he would be excluded from great parts of normal life (school, cinema, cafe, playpark, soft play area). I wish you luck, I know how horrible it is.