Can I file taxes long before I leave?

It might be a dumb question, but I feel like asking anyway:

How early can I file taxes? Does anyone care? I’m going to leave Taiwan soon, but I don’t know when. So hypothetically, let’s say I was going to leave Taiwan in December but wanted to file my taxes tomorrow; can it be done? Sometimes I think it would be easier just to file way early, collect what I can and write off the rest (I’m not in a good situation here). I mean, do they verify when you are actually leaving Taiwan, or could you file any time and then deal with the rest later?

Are there rules, regulations, recommendations about this?