Just to clarify - by "eligibility limit" I meant that with Mathcounts if DS is a 6th grader this year, his eligibility gets cut off three years from now, even if I claimed he was held back during that time. Once you start MathCounts, you have a three year eligibility window and then you're done. With the AMC tests, you can start early and just keep doing them every year until you reach the end grade (8 for the AMC-8, 10 for the AMC-10, and they have age cutoffs to go with those), but they don't care that it could mean you've taken the AMC-8 six years in a row, just as long as the last one isn't too late.
