No. Tags should give an indication about the question's topic(s), nothing else. That's the reason the
homework tag is deprecated too, for instance. If you want to indicate that you're a beginner in order to get answers at your level of knowledge, say so in the question.
If there would be any need to have an indication about difficulty level, like the number of chef's caps in kitchen recipes, that should be something separate, but I don't advocate this. Like Olin says levels can be different for different answers, and there's nothing wrong with that; answers should be as widely useful as possible. So if you're lost at the second sentence of an answer, move on to the next.
After all, if you're looking up questions it will be based on "555" rather than "beginner".
PS: I notice there are 25 questions tagged
learning, I think that tag should go as well.