This is said in the FAQ
Privileges not tied to a specific threshold
- To answer protected questions, you need to gain 10 reputation on the site – the association bonus does not count. In other words, the reputation threshold for answering protected questions if you have the bonus is 110, not 10.
If my Maths and English aren't too bad,
gained 10 = 1 + 10 = 11 (or 111 with assoc-bonus). But it says 110, as well as a lot of other places:
Another FAQ: What is a “protected” question?
Who can answer a protected question?
Users with 10 or more reputation can answer a protected question. However, the +100 account association bonus is ignored for this check.
In practice the check is all bodged up and inconsistent. In particular, if you associate an account and get no bonus (cause you have less than 200 rep) we arbitrarily decide that you need 111 rep to post answers.
Those conflicts are really embrangling. Question:
Is it 10/110 or 11/111 (new user / user with assoc bonus)?