How many times in one day may a layman receive Holy Communion? For instance, if someone were to attend a morning Mass and receive Holy Communion then, would it be acceptable or not to receive Holy Communion at a later Mass in the afternoon?
This is an easy question. Clear-cut, Church teaching, not a disputed question OR matter of opinion. I'll also point out: I speak for the Church here. This is not my opinion. This is Traditional, pre-Vatican II Catholic teaching.
You may only receive Holy Communion ONCE per day.The only exception is if you are in danger of death. Even if you went to morning Mass and received, and then found yourself in danger of death later that day, you could receive Viaticuм from a priest.
In short, Viaticuм doesn't count towards your "one Holy Communion per day".