When may lay people receive Communion outside of Mass? The Consilium tells you:
33. a. The faithful are to be led to the practice of receiving communion in the actual eucharistic celebration. [See Pius XII, Encycl. Mediator Dei: Acta Apostolicae Sedis 39 (1947) 565-566.] 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 norms 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. [See Paul VI, Motu Proprio Pastorale munus [I] no. 4. Secretariat of State, Pontifical Rescript Cum admotae I, no. 1.]
I wonder if this following applies these days to Communion to the sick, the most frequent time in which the Sacrament is distributed outside of Mass:
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).
And finally, we have Rome’s early post-conciliar concession for Communion services:
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.