How do you reply to a wedding invitation?

An RSVP looks like a formality and is actually a logistics document. Behind each name sit a seat, a meal, a place card and a per-head charge that the couple pay whether you turn up or not.

This article covers when to reply, how to fill in a card or an online form, what to do about a plus one that is or is not offered, and the situations that need a sentence rather than a tick: a maybe, a late change, a dietary requirement, a child.

Within a week is the standard and it is easily achievable, because almost everyone knows immediately whether they intend to go.

The reason for speed is not politeness for its own sake. Couples build the guest list in tiers, and a decline that arrives early lets somebody else be invited in good time. A decline that arrives four days before the deadline turns a second invitation into an obvious one.

Wedding invitations typically go out eight to twelve weeks before the day, with a reply deadline four to six weeks before. Anything you send inside two weeks of the deadline is already late from the caterer's point of view, even though it is technically on time.

Use the channel on the invitation. A couple who set up an online form and receive nine text messages have to transcribe nine text messages, and that is where names get lost.

A printed reply card. Fill in every line. The name line means the names of the people attending, not the household. Tick the accept or decline line clearly, add dietary requirements if there is a box, and post it. If a stamped envelope came with it, use that one.

An online form. Complete it in one go, including the optional fields. Song requests and dietary boxes are there because somebody needs the answer.

Email or a phone number. Write in full sentences and include the names of everyone attending. A reply saying yes from a number the couple do not have saved is a small mystery to solve later.

Nothing specified at all. Reply to whoever sent the invitation, in writing, so there is a record. Verbal acceptances at a family gathering are the ones that disappear.

Where the couple have set up a wedding website, that is almost always the channel they want, and it will usually collect the dietary and accommodation answers at the same time, which saves both sides a later exchange.

The names on the envelope and on the inner card are the guest list. This is the single most common source of friction, and it is almost always a misreading rather than a snub.

1. Two names, no and guest. Two people are invited. Not your children, not your new partner unless they are named.
2. Your name and guest. You may bring one adult. Give their full name in the reply so a place card can be printed.
3. The Smith family. The household, children included.
4. Your names only, children not listed. The wedding is adults only. This is not an oversight and does not need testing.
5. An evening invitation. You are invited to the part named on the card. Arriving for the ceremony is a genuine problem for the seating plan.

If you are unsure, ask once, directly, and accept the answer. What does not work is replying for three when two were invited and letting the couple correct you. That puts the awkward conversation on the people who are already paying for the day.

And if you are given a plus one you do not need, say so. A declined plus one is a seat back, and couples appreciate it far more than they let on.

Short is correct. Two sentences on a card, three in a message.

Accepting, formal card: the names, then a line such as accepts with pleasure. Nothing else is required.

Accepting, in writing: We would love to come. That is Anna and Tom, and Tom is vegetarian. Thank you for asking us.

Declining: keep the reason brief or leave it out. We are so sorry we cannot be there, we will be thinking of you both. An explanation of three paragraphs invites a negotiation nobody wants.

Not yet certain: name the date. We are trying to move a work trip and will know by the tenth. Is that in time? That is a usable answer; a silence is not.

Add the practical facts at the same time as the answer, not later. Dietary requirements, an access need, a child's age if children are invited, and whether you need accommodation are all things the couple will otherwise have to chase individually. Sending them in the same message saves four exchanges.

Two things not to put in a reply: a request to bring somebody who was not invited, and a comment on the date, the venue or the cost of getting there.

Circumstances change and couples know it. What matters is the speed and the honesty of the message.

From yes to no. Tell them the moment you know, by message or phone, not through a third party. Say sorry once. If it is inside the final two weeks the couple are almost certainly paying for your meal regardless, and many guests send the gift anyway; that is a kindness rather than an obligation.

From no to yes. Ask rather than announce. We find we are free after all, is there still room? Seating plans and catering numbers close earlier than people think, usually two to three weeks before, and the answer may genuinely be no.

A change of plus one. Tell them the new name as soon as you have it, because place cards are printed from that list.

Illness on the day itself is the one case where a text at seven in the morning is not only acceptable but essential. Two empty seats at a table of eight are noticed; two empty seats the caterer knew about at eight o'clock are not.

Finally, the courtesy that costs nothing: if you accepted and attended, a message the following week saying it was a good day is worth more than most of the cards. Couples spend a year on this and hear almost nothing afterwards.