First, if you are not in the state of grace, don’t just go to Holy Communion anyway. That’s a sacrilege and a mortal sin. Those of you who are lax about Mass attendance need to remember that not going to Holy Mass on Sundays and other days of obligation, when you could go, is a mortal sin. Go to confession and then make your good Holy Communion. We all know the bit about making a perfect act of contrition… maybe you can do that and maybe you can’t. That’s up to you. But God cannot be fooled. If you know you shouldn’t receive then don’t.
Second, if you know you cannot go to Holy Communion that does not mean you are excused from going to Mass. You still have the obligation to attend Mass on Sundays and days of obligation even if you can’t receive. That’s why they are called days of obligation. It is your attendance that is obligatory, not Communion.
Third, observe the Eucharistic Fast, which is one hour before Communion not one hour before the beginning of Mass. If you want to fast longer, fine. One hour is the law, unless you are sick, etc. etc. Remember, to receive Communion we have to be disposed in our souls (by being in the state of grace) and in our bodies (by observation of the fast which pertains to our state in life).
Fourth, if you are in the state of grace you may receive Holy Communion at Midnight Mass and also receive once more if you also go to Christmas Mass during the day (even if “Midnight Mass” begins at or after Midnight, that is, on the same calendar day).
The 1983 CIC c. 917 for the Latin Church states that you can receive twice in a day, “iterum… again”. Iterum doesn’t mean “repeatedly”. So long as the second time is in the context of a Mass you attend, you can receive one more time. A third time must be in death of your death.
Fifth, all this this pertains both to the old Mass, the Extraordinary Form, as well as the new Mass or Novus Ordo.
I write this because I noted the 2011 Ordo for the Extraordinary Form put out by the SSPX states (and here I make the assumption that their 2010 Ordo says the same thing):
Those receiving Communion at this Mass after Midnight may not receive again at Masses attended on Christmas Day.
That is not what Holy Church’s law says for Latin Church Catholics. Eastern Catholic laws are probably stricter, I don’t know. I don’t doubt for a moment that Easterners will chime in.
That doesn’t mean that you must receive. It only means that you can receive, contrary to what is printed in that Ordo. It is otherwise a pretty good source.
If you hear an announcement or read something about that in a bulletin, now you know the truth of the matter.