Candidacy is usually referred to the qualification required for a candidate to apply for a specific post.
However, does "Candidacy " sometimes refer to the person as well? Can I say "Candidacy for this open position"? Is that acceptable for a native speaker?
Candidacy or Candidature is a noun and it means the whole process of applying for (a position). You could say Candidacy for this open position but it would not be referring to a person. The proper form would be:
His candidacy for this open position was surprising to all.
Candidacy does not refer to persons: it is a status attributed to persons, the fact or manner of being candidates, not the candidates themselves.
Thus, one may say that “X announced her candidacy”, meaning that she has assumed the status and undertaken the role of candidate for an office. When the newspapers discuss her candidacy they are not talking about the candidate herself but about such matters as the manner in which her campaign is run and her likelihood of achieving the office for which she is campaigning.
Likewise, candidacy does not refer to the office for which one is a candidate: it is the status of being considered or considerable for the position.
Accordingly, in announcing an opening it is not referred to as a candidacy: that is the status of the persons who apply for the opening. The institution does not advertise a candidacy, but a vacancy or position or appointment or some such thing, and it does not seek candidacy, it seeks candidates.
In some cases, candidacy is officially defined. For instance, in many universities a graduate student who has satisfactorily completed a required curriculum (and the required paperwork!) is formally admitted to candidacy for an advanced degree. This doesn't mean that the student has earned the degree, only that she is now regarded as worthy of being considered for the degree and is now admitted to the advanced studies in which she may actually earn the degree.
So in advertisements for academic positions you will sometimes see things like “Doctorate or candidacy required”, meaning that only persons who have achieved at least candidacy for the doctoral degree will be considered for the appointment.
"Candidacy" refers to the state of being a candidate, not to the person.
You can say, "He announced his candidacy for mayor", meaning, he said that he was running for the office. You can also say, "He is now a candidate for mayor". But you can't say, "He is a candidacy for mayor".
It's function in a sentence is similar to the word "laziness". You can say, "He admitted his laziness", which is parallel to "He announced his candidacy." But you wouldn't say "He is a laziness".
"Candidacy for this open position" is a title and not a complete sentence, so it's not clear exactly what the role of the word is there. If the point is to say that we are now seeking people to fill this position, I might say "Candidates sought for this open position".
"Candidacy" doesn't mean "qualification required to apply". You wouldn't say, "Four years experience is a candidacy for the accountant position" or anything like that.
Yes you can do that. Candidacy means "the state of being a candidate". It is used in a way when somebody is going to compete for a post. Like:
1) I gave wholehearted support to her candidacy.
2) He is expected to announce his candidacy.
But when you are giving advertisement like you said, you would probably go with:
Need candidates for Customer Care post.
However if you are inclined to using "candidacy", you may say:
Candidacy for telemarketing executive required for Customer Care post.
applicants for some other post, Y, must also be candidates for X., I did not get this part! Are you suggesting Candidacy required for Customer Care post. means the candidate must be an existing/former employee of a telemarketing company? Is it like this you mean to say?