Can a business reply to an Instagram DM after 24 hours?

Only in limited cases. Meta allows normal replies for 24 hours after the person's last message. After that, a reply only goes through if a person is responding to that specific conversation using the human agent tag, which Meta allows for up to seven days. Automated or bulk follow-ups after 24 hours aren't allowed.

The window resets every time the person sends a new message, so an active conversation stays open.

What this means for agencies:

• Leads and complaints need a reply the same working day, on every client, including weekend messages.
• If you're waiting on the client for an answer (a price, a date), chase the client before the customer's window closes.
• The human agent tag is for genuinely slow cases, like a refund that needed review. Using it for sales follow-ups or automated nudges breaks Meta's rules.

The full method is in Instagram's 24-Hour Messaging Window: What Every Agency Gets Wrong.