Answer an invitation with a formal RSVP written in the third person. State the full names of those invited, whether to accept with pleasure or regret being unable to accept the kind invitation, and finish with the full names of the hosts and the date of the event.
A written response is not required if the invitation included a response card with boxes to select whether to accept or decline the invitation. Include any additional information requested in the original invitation, such as selecting a meal option, responding for other guests listed on the invitation, or providing the name of an unnamed guest.
Respond to the invitation as promptly as possible so the hosts know how many guests to expect. A declined invitation often means an opening to invite another guest which requires ample time to send out the new invitations.