Hi, The word minimum is countable (plural minimums/minima) so you should use "a" in front of minimum. In some other uses of minimum you don't need an "a" before it (I'm on minimum wage) because they are rather idimatic expressions. But I don't think that your sentence is well written.
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Ivanhr I'm on a/- minimum wage)Both are acceptable, but I'd rather use one with an article.