What is proper etiquette for RSVPing to a wedding?

Short answer

Reply as soon as you can, ideally within a few days of receiving the invitation. Always use the method the couple asked for, whether that is a card, email or website. Never assume a plus one unless it is clearly offered.

The golden rule is to respond promptly. Couples need final numbers for the venue, caterers and seating plans, so a quick reply is a kindness, not a chore. Aim to send your RSVP within a week of the invitation arriving, and definitely before the date printed on the card.

Use the reply method the couple has chosen. If they sent a stamped card, post it back. If they gave a website or email, use that. Do not text a friend or mention it in passing at work, as messages get lost. If you are unsure whether you can bring a partner, check the envelope and the invitation wording. If it says just your name, it is for you alone. If it says "and guest", you may bring someone.

If you cannot attend, say so honestly and kindly. A simple "we would love to, but we cannot make it" is enough. Do not over-explain. If you have a dietary requirement or a mobility need, mention it on the RSVP card or in the notes section if there is one. If you need to change your reply later, contact the couple directly as soon as possible. They will understand, but the earlier the better.