Part II-3. Communion of the Faithful
Communion of the Faithful at Mass
31. The faithful share more fully in the celebration of the eucharist through the sacramental communion. It is strongly recommended that they should receive it as a rule in the Mass itself and at that point in the celebration which is prescribed by the rite, that is, right after the communion of the priest celebrant. 
In order that the communion may stand out more clearly even through signs as a participation in the sacrifice actually being celebrated, steps should be taken that enable the faithful to receive hosts consecrated at that Mass. 
It is proper for the priest celebrant especially to be the minister of communion; nor should he continue the Mass until the communion of the faithful has been completed. Other priests or deacons may, if need be, assist the priest celebrant. 
Communion Under Both Kinds
32. Holy communion has a more complete form as a sign when it is received under both kinds. For in this manner of reception (without prejudice to the principles laid down by the Council of Trent,  that under each element Christ whole and entire and the true sacrament are received), a fuller light shines on the sign of the eucharistic banquet. Moreover there is a clearer expression of that will by which the new and everlasting covenant is ratified in the blood of the Lord and of the relationship of the eucharistic banquet to the eschatological banquet in the Father's kingdom (see Mt 26:27-29).
From now on, therefore, at the discretion of the bishops and preceded by the required catechesis, communion from the chalice is permitted in the following cases, granted already by earlier law  or granted by this Instruction:
1. to newly baptized adults in the Mass following their baptism; to confirmed adults in the Mass of their confirmation; to baptized persons who are received into the communion of the Church;
2. to the spouses in the Mass of their wedding;
3. to those ordained in the Mass of their ordination;
4. to an abess in the Mass of her blessing; to the consecrated in the Mass of their consecration to a life of virginity; to religious in the Mass of their first profession or of renewal of religious profession, provided they take or renew their vows within the Mass;
5. to lay missionaries in the Mass at which they are publicly sent out on their mission and to others in the Mass in which they receive an ecclesiastical mission;
6. in the administration of viaticum, to the sick person and to all who are present when Mass is celebrated, with conformity to the requirements of the law; in the house of the sick person;
7. to the deacon, subdeacon, and ministers exercising their proper office in a pontifical or solemn Mass;
8. when there is a concelebration:
a. to all exercising a genuine liturgical ministry in that concelebration; even lay people, and to all seminarians present;
b. in their own churches, to all members of institutes professing the evangelical counsels and members of other societies in which the members dedicate themselves to God either through religious vows or oblation or promise, and also to all who reside in the house of the members of these institutes and societies;
9. to priests present at large celebrations and unable to celebrate or concelebrate;
10. to all groups making retreats, in a Mass celebrated especially for those actually participating; to all taking part in the meeting of some pastoral commission, at the Mass they celebrate in common;
11. to those listed under nos. 2 and 4, in the Mass of their jubilee;
12. to the godfather, godmother, parents, and spouse of baptized adults, and to the laypersons who have catechized them, in the Mass of initiation;
13. to the relatives, friends, and special benefactors taking part in the Mass of a newly ordained priest.
Communion Outside Mass
33. a. The faithful are to be led to the practice of receiving communion in the actual eucharistic celebration.  But priests are not to refuse to give communion to those who request it for a just reason outside Mass. This is permissible even in the afternoon hours with the permission of the local bishop, in keeping with the nor of the Motu Proprio Pastorale munus no. 4, or by permission of the supreme moderator of a religious institute, in keeping with the norm of the Rescript Cum admotae art. 1, no. 1. 
b. When communion is distributed outside Mass at the prescribed hours, a short celebration of the word of God may, if opportune, precede it, in accordance with the provisions of the Instruction Inter Oecumenici (nos. 37, 39).
c. When Mass cannot be celebrated because there is no priest available and communion is distributed by a minister with the faculty to do this in virtue of an indult of the Apostolic See, the rite laid down by the competent authority is to be followed.
The Way of Receiving Communion
34. a. In accordance with the custom of the Church, the faithful may receive communion either kneeling or standing. One or the other practice is to be chosen according to the norms laid down by the conference of bishops and in view of the various circumstances, above all the arrangement of the churches and the number of the communicants. The faithful should willingly follow the manner of reception indicated by the pastors so that communion may truly be a sign of familial union among those who share in the same table of the Lord.
b. When the faithful communicate kneeling, no other sign of reverence toward the most holy sacrament is required, because the kneeling itself expresses adoration.
When they receive communion standing, it is strongly recommended that, approaching in line, they make a sign of reverence before receiving the sacrament. This should be done at a designated moment and place, so as not to interfere with the coming and going of the other communicants.
Sacrament of Penance and Communion
35. The eucharist should also be proposed to the faithful "as a remedy that frees us from our daily faults and preserves us from mortal sins."  They should also receive an explanation of how to make use of the penitential parts of the Mass.
"Those wishing to receive communion should be reminded of the precept 'let them examine themselves' (1 Cor 1:28). Ecclesiastical custom shows that this examination is necessary so that none who are conscious of having committed mortal sin, no matter how contrite they believe themselves to be, should approach the holy eucharist without first making a sacramental confession."  "In a case of necessity, however, and when no confessor is available, a person should first make an act of perfect contrition." 
The faithful are to be constantly encouraged in the practice of receiving the sacrament of penance outside Mass, especially at the scheduled hours, so that the administration of the sacrament may be unhurried and genuinely useful and that people will not be impeded from active participation in the Mass. Daily or frequent communicants should be instructed to go to confession regularly, depending on their individual needs.
Communion on Special Occassions
36. It is most fitting that whenever the faithful are beginning a new state or a new way of working in the vineyard of the Lord, they take part in the sacrifice through sacramental communion, thereby dedicating themselves again to God and renewing their covenant with him.
This may well be done, for example, by the assembly of the faithful when they renew their baptismal vows at the Easter Vigil; by young people when they do the same thing in the presence of the Church, in a manner in keeping with their age; by the bride and groom when they are united by the sacrament of marriage, by those who dedicate themselves to God when they pronounce their vows or other forms of commitment; by the faithful when they are to devote themselves to apostolic service.
Frequent and Daily Communion
37. Since "it is clear that the frequent or daily reception of the most blessed eucharist increases union with Christ, nurtures the spiritual life more richly, forms the soul in virtue, and gives the communicant a stronger pledge of eternal happiness, pastors, confessors, and preachers . . . will frequently and zealously exhort the Christian people to this devout and salutary practice." 
Private Prayer After Communion
38. On those who partake of the body and blood of Christ the gift of the Spirit is poured out abundantly like living water (see Jn 7:37-39), provided communion is received both sacramentally and spiritually, that is, in living faith that works through love. 
But the union with Christ that is the reason for the sacrament itself is to be sought not only at the time of the eucharistic celebration but is also to be prolonged all during the Christian's life. This means that the faithful of Christ, dwelling constantly on the gift they have received, should live their daily lives in continual thanksgiving under the Holy Spirit's guidance and should produce more abundant fruits of charity.
In order to continue more surely in the thanksgiving that in Mass is offered to God in an eminent way, those who have been nourished by communion should be encouraged to remain for some time in prayer. 
39. Communion received as viaticum should be considered as a special sign of sharing in the mystery celebrated in the Mass, the mystery of the death of the Lord and his return to the Father. Viaticum seals the faithful in their passage from life with the pledge of the resurrection as they are strengthened by Christ's body.
Therefore, the faithful who are in danger of death from any cause whatever are bound by precept to receive communion;  pastors must guard against delay in the administration of this sacrament and see to it rather that the faithful receive it while still in full possession of their faculties. 
Even if the faithful have already communicated on the same day, and then the danger of death arises, it is strongly recommended that they receive communion again.
Communion of Those Unable to Come to Church
40. It is right for those prevented from being present at the celebration of the community eucharist to receive the eucharist often; in this way they will also realize that they are part of the eucharistic community, borne up by its charity.
Pastors should take care that the sick and the elderly be given the opportunity, even if they are not gravely ill or in danger of death, to receive the eucharist often, even daily if possible, especially during the Easter season. They may receive communion at any hour of the day.
Communion Under the Form of Wine Alone
41. In case of necessity and at the discretion of the bishop, it is permissible for the eucharist to be given under the form of wine alone to those who are unable to receive it under the form of bread.
In this case the celebration of Mass in the presence of the sick person is permissible, at the discretion of the local Ordinary.
If, however, Mass is not celebrated in the presence of the sick person, the blood of the Lord should be preserved in a properly covered chalice and placed in the tabernacle after Mass; it should not be carried to the sick person unless it is enclosed in a container that prevents any danger of spilling. In administering the sacrament, the method best suited to the individual case should be chosen from among those indicated in the rites for use in distributing communion under both kinds. If, after communion has been given, some of the precious blood remains, the minister is to consume it; he is also to see to the required ablutions.