I have filed a chapter 13 and I am supposed to have a confirmation meeting March 31. Do I need to wait until after the meeting or can I file my taxes now?

There is no requirement to wait that I am aware of, you can confirm it with your attorney. But filing should not effect your bankruptcy

There have been times and places where the attorney for the Trustee has claimed tax refunds as property of the estate. You could wait until after the confirmation hearing, when you can read the order of confirmation; or you could ask your attorney.