The Lectionary for Sundays is arranged in a three-year cycle, in which Year A always begins on the First Sunday of Advent in years evenly divisible by three. (For example, 2026 divided by 3 is 6,078 with no remainder.  Year A, therefore, begins on Advent Sunday of this year.)

The Psalms and Lessons appointed for the Sundays and for other major Holy Days are intended for use at all public services on such days, except when the same congregation attends two or more services.  Thus, the same Lessons are to be read at the principal morning service, whether the Liturgy of the Word take the form given in the Holy Eucharist, or that of the Daily Office.

For more detail you can read more concerning the Lectionary on page 888 in the Book of Common Prayer found in the seat back of the pew.