When you need to miss work at the last minute, the best approach is to communicate as quickly and effectively as possible. A phone call is often the most direct and reliable way, but depending on your workplace culture, an email or message might also be appropriate. In your communication, be brief but clear about why you can't make it, whether it’s due to illness, an emergency, or another sudden issue. You don’t need to go into too much detail if the situation is personal, but letting your boss know the nature of the problem (e.g., 'I'm dealing with a family emergency') helps them understand the urgency. Make sure to also provide an estimated timeline for when you'll be able to return or follow up with more information later. Offering to help remotely or make up the time later can show your commitment, even in unforeseen circumstances. Respecting both your needs and your boss’s time ensures a smooth handling of unexpected absences.