I don’t think that any kind of a response is needed or expected.

It depends so much on how the condolences were offered. Obviously, if it is in person, a warm handshake or other verbal acknowledgement is done. If it is via Facebook, I’d probably post a thank you on the post or if there are several, a thank you post in general. I wouldn’t feel that a thank you note is necessary for a sympathy card. I got several when each of my parents died and appreciated them but didn’t write a response.

I thank them usually in the manner it was expressed. So if someone sends their condolences on FB, I’ll thank them on FB. If it’s by text message I’ll reply with a text. If they send a card, then I’ll reply with a text or a phone call depending on my relationship with that person.

What I would do is the bare minimum, because grief is complicated and condolences are to comfort the bereaved, not burden them.

I define “bare minimum” as “short response via the same medium, unless it’s paper”. So I’d reply with a simple “Thank you.” to any texts or emails. Probably not immediately, more likely a few weeks out. For social media, I’d write just a public acknowledgment at some point, in a month or so.

I would not reply to any cards. I don’t think anyone would expect a reply.

Related: If condolences or offers of help are overwhelming, it can help to appoint a trusted friend or family member to manage communication. When my husband was in the hospital a couple of years ago, my sister coordinated the pet sitting schedule and I could direct any offers of help to her. That was hugely helpful.

If I receive a card, I don’t acknowledge it. As people said above, if a text or Facebook post, I’ll jot off a short sentence.
People mean well and want you to know they are thinking of you, but it can be overwhelming.

I don’t think anything is or should be expected when I’m grieving. I might respond in some way and I might not. Depends on the moment and my strength at the time. A thank you or acknowledging a card or well wishes might come immediately or weeks after or never.

When one of my close friends died her daughters periodically acknowledged when people would post on Facebook about their mom. They would write how much they appreciate people thinking about their mom and they sometimes acknowledged condolences to the girls. It’s like an unexpected treat when the daughters would respond, so that taught me how well it is received when these things are acknowledged, but sometimes I am just not up to it.

I don’t think it’s anything like acknowledging gifts for birthdays or weddings if we were to compare social obligations and etiquette to another experience where someone does something for you.

Facebook and text is great that you can just click a heart or a like, and they know you saw what they wrote.

For those attending the funeral or those who took time to send a card, I write a thank you card.
If its a text, call or on socials, I respond there.

I agree with the first reply.

I received two cards in the mail and several messages on Facebook when my mother passed away. I thanked everyone using fb messenger. I appreciated them taking time to reach out. I had half-siblings who did nothing so any acknowledgment from others was appreciated.

(One of the cards I received was from @gailcalled. She quickly became my surrogate mother.)