How to address a couple that isn't married?

For an unmarried couple, write each name on its own line on the envelope. Use their preferred titles, such as Ms, Mr, Mx or Dr, followed by their full name. If they share an address, put both names on the front, one above the other, with the address below.

If you know one person better, put that name first. If you know them equally, alphabetical order by surname works well. Avoid using 'and' between names unless they are married or in a civil partnership, as that can imply a legal tie.

For the inner envelope, if you use one, you can write just their first names on separate lines. This feels friendly and personal. If they have different surnames, that is fine, just use each person's own surname. If they have children living at home, you can add the children's names on a separate line after the adults, or include them on a separate invitation if they are invited.