Do you need to qualify to enter a national event in S/ST?

[65Shoebox]

So.. as we embarq on year # 2 of S/ST racing and begin to plan the calendar, I have a question I am sure someone here can assist with. Sorry if it is posted elsewhere, but I searched and can't locate the answer.

Is it necessary to be invited or qualify via divisional points to run at a national event? If so, what is the criteria?

Thanks!