To be taxed with Mary his espoused wife, being great with child.

People's New Testament

2:5 To be taxed with Mary. Women had to be enrolled also and were subject to the poll tax. Mary was of the line of David, and hence would also have to go to Bethlehem.

King James Translators' Notes

taxed: or, inrolled

Jamieson-Fausset-Brown Bible Commentary

5. espoused wife-now, without doubt, taken home to him, as related in Mt 1:18; 25:6.

Matthew Henry's Concise Commentary

2:1-7 The fulness of time was now come, when God would send forth his Son, made of a woman, and made under the law. The circumstances of his birth were very mean. Christ was born at an inn; he came into the world to sojourn here for awhile, as at an inn, and to teach us to do likewise. We are become by sin like an outcast infant, helpless and forlorn; and such a one was Christ. He well knew how unwilling we are to be meanly lodged, clothed, or fed; how we desire to have our children decorated and indulged; how apt the poor are to envy the rich, and how prone the rich to disdain the poor. But when we by faith view the Son of God being made man and lying in a manger, our vanity, ambition, and envy are checked. We cannot, with this object rightly before us, seek great things for ourselves or our children.