For Proper Reception, Catholics should . . .

• have fasted for one hour.

• not be conscious of grave sin.  A person who is conscious of grave sin is not to receive the Body and Blood of the Lord without prior sacramental confession except for a grave reason where there is no opportunity for confession.
       In this case, the person is to be mindful of the obligation to make an act of perfect contrition, including the intention of confessing as soon as possible (canon 916).

" ... although separated from us, yet possess true sacraments, above all - by apostolic succession - the priesthood and the Eucharist, whereby they are still joined to us in closest intimacy." A certain communion in sacris, and so in the Eucharist, "given suitable circumstances and the approval of Church authority, is not merely possible but is encouraged." (Unitatis Redintegratio 22 §3)

The Orthodox Churches may receive Holy Communion with us; please consult the priest before Mass.

The Catechism of the Catholic Church §1399

   Ecclesial communities derived from the Reformation and separated from the Catholic Church, "have not preserved the proper reality of the Eucharistic mystery in its fullness, especially because of the absence of the sacrament of Holy Orders.  However these ecclesial communities, "when they commemorate the Lord's death and resurrection in the Holy Supper . . . profess that it signifies life in communion with Christ and await his coming in glory." (Unitatis Redintegratio 22 §3)

   It is for this reason that, for the Catholic Church, Eucharistic intercommunion with these communities is not possible. If you choose to, you may come forward for a blessing from the priest or deacon with your arms crossed over your chest.

The Catechism of the Catholic Church §1400