To receive Holy Communion licitly, you must be: (1) a baptized Catholic; (2) in a state of grace — not conscious of any unconfessed mortal sin; (3) observing the Eucharistic fast; and (4) holding the proper disposition — that is, believing the Church's teaching on the Real Presence and approaching with reverence and faith. If all four conditions are met, you are not only permitted but encouraged to receive.

The current law requires abstaining from food and drink — except for water and medicine — for one hour before receiving Communion. The hour is counted to the time you receive, not to when Mass begins. So if Mass starts at 10am and lasts an hour, you would need to have stopped eating by 10am at the latest. Water never breaks the fast. Medicine never breaks the fast.

The fast was historically much longer (originally from midnight; later reduced to three hours in 1964; reduced again to one hour in 1973). The one-hour rule reflects the Church's pastoral concern for those attending multiple Masses, the sick, and those who work through mealtimes.

Those who are elderly, ill, or who care for them may receive Communion even if they have consumed food, drink, or medicine within the hour — without any time restriction. This provision exists so that illness or the demands of caregiving never become an obstacle to receiving Christ. If you are in this situation, simply receive.

If you are aware of having committed a mortal sin — and have not yet gone to Confession — you may not receive Communion. This is not optional or a suggestion. Receiving in a state of mortal sin is itself a mortal sin (receiving unworthily, cf. 1 Corinthians 11:27–29). The remedy is simple: go to Confession before Mass. If Confession is genuinely impossible that day, you may make a perfect act of contrition with the firm intention to go as soon as possible — but you should still go to Confession.

Catholic Communion is reserved for Catholics. This is not a matter of hospitality or welcome — it is a matter of truth. Receiving Communion is a sign of full communion with the Catholic Church: one faith, one baptism, one Eucharist. Extending Communion to those not in that full communion would misrepresent a unity that does not yet exist. Non-Catholics at Mass are warmly welcomed to pray, to be present, to receive a blessing (by crossing their arms over their chest when approaching the Communion line) — but not to receive the Eucharist.

There is a narrow exception: Eastern Christians not in full communion with Rome who share Catholic Eucharistic faith and cannot access their own ministers may in some circumstances receive — but this requires their own judgment and is governed by specific canon law provisions.

Those who have been formally excommunicated or interdicted by the Church are prohibited from receiving Communion. This applies to a very small number of people in specific canonical situations (e.g., apostasy, schism, certain grave offenses). Excommunication is a medicinal penalty intended to bring about repentance and reconciliation — it is not permanent for most offenses. If you are unsure whether a canonical penalty applies to you, speak with a canon lawyer or your bishop.

In the United States, both ways of receiving are fully valid and licit:

On the tongue: The older and universal practice. Open your mouth, extend your tongue slightly, and allow the minister to place the Host on it. Then consume immediately.

In the hand: Permitted in the U.S. since 1977. Place one hand over the other, palms up, to form a "throne." Receive the Host in the upper hand. Step to the side and consume immediately — do not walk away with the Host in your hand.

No minister may refuse Communion to someone who presents themselves properly in either manner. The choice is yours; neither is more or less reverent by definition.