女&男 both seem age specific since there is a の子 ver for both. So is it safe to say 女性/男性 are what I would say if I was referring to the entire sex regardless of age? Is that would would be put in officials bills concerning diff sexes?
The concept, 'sex,' in Japanese would be 性別(せいべつ). The Japanese Wikipedia article on the topic says:
So, depending on what you are referring to, it could be 男性 and 女性 or オス and メス respectively. The article has a section that specifically addresses human sex. I'll quote it here:
From this sentence, it would appear that 男性・女性, as well as おとこ・おんな and 男子・女子 are all acceptable for differentiating sex.
However, since you're asking what pair of words would be used on official forms and the like, and for that it would be 男性・女性. For example, see this online Visa correction form.
You'll notice that item #4 性別 gives the options 男性 and 女性. I've also seen them abbreviated to just 男 and 女 to save space on the page.