As you said, the company says it pays bonus "based on performance of the company for the year and number of days spent offshore by the employee"
Being paid offshore allowance and actually working offshore are two different things. As you see, there are times when you still get the bonus without actually going.
This may have been a deliberate ploy by them or it was written by someone who didn’t realise the difference between being paid offshore bonus and actually being offshore.
It may be worthwhile approaching (or several of you would be better) and ask if they will correct the wording in their bonus scheme.
It is up to the Company how much bonus they pay (remember they dont have to pay any!) but the point of the bonus is to encourgare workers, so if they wish to encourage you, then they will correct it 🙂
Thinsub – Offshore bonus/offshore allowance, call it what you want. They are not holding anything back. Its just a different way of getting paid. Think of it as the salary being a "retainer" and the offshore part is paid when you do work.