This is from a CPE up date course I took "taxpayer does not have a qualifying child, he or she must: – Be at least 25, but under age 65, at the end of the tax year (if Married Filing Jointly, only one spouse needs to meet this age test."
I was looking for a table that gives the AGI that would provide the maximum $506 for a no-qualifying child. Similarly the AGI for $3733 maximum for one qualifying child. Etc. I have seen the link you provided, but couldn't get this more specific info.