Someone asked a question about ‘how late is too late to arrive at Mass and still receive communion’.
There is no law governing this, but there are theologians who have given direction on this and related questions. Father Herbert Jone is one. He was also a canonist. In “Moral Theology” he wrote:
“In order that the grave obligation of hearing Mass on Sundays
and Holydays be fulfilled certain conditions are required on thepart of the Mass and on the part of the attendants. – One may beexcused from assisting at Mass for a proportionately good reason.I. On the part of the Mass of obligation the followingis required:1. It must be a complete Mass, i.e., assistance at itmust extend from the beginning of the Mass to thelast blessing.A venial sin is committed by voluntarily omitting an unimportantpart of the Mass, e.g., from the beginning of the Mass to theOffertory exclusive, or the part that follows the Communion, oreven the part which precedes the Epistle together with that whichfollows the Comm union.A mortal sin is committed by missing an important part voluntarily,e.g., that which precedes the Gospel together with whatfollows Holy Communion, the part extending from the beginningof the Mass to the Offertory inclusive, the part of the Canon thatprecedes the Consecration, or the part between the Consecrationand the “Pater Noster,” or the Consecration alone; but probablynot the Communion alone. It is held that momentary and necessarywithdrawal during the Consecration would be excusable. – Whoevermisses an important part must supply this part in a laterMass on the same day.The obligation to hear Mass is not fulfilled by him who is notpresent at the Consecration. But if one is present at the entire Massexcept the Consecration, it may be presumed that the Church wouldnot oblige him to attend another Mass. – If one, even t!.ough hebe late for Mass arrives before the Consecration he must remainfor the rest of the Mass in case he cannot assist at a later Mass,since he can still essentially fulfill his Sunday obligation; but ifone were so late as to miss the Consecration he would not be
obliged to remain for the rest of the Mass.”
I conclude that if you are culpable of sin, even if venial, for missing an important part of Mass, you should abstain from communion.