Kids birthdays... who do you invite?

I was following along a post on my local year 1 school FB group and the question came up about who you 'have' to invite to parties. Last year in kindy my son was invited to most parties, but then there were a few that he missed out on, and boy did that cause chaos. This year I have felt that they have more established friendship groups so perhaps inviting just close friends is now acceptable. And possibly the best way to achieve this is by personally giving invitations to the parents rather than have the child or teacher hand them out in class? 

What has worked for you and what are your birthday invitation rules that are working for your school group?