It is always flattering when you receive an invitation from a friend or family member. Unfortunately, you can't accept every invitation that comes your way. Whether you have a previously scheduled appointment, don't want to travel to the specific event or have some other reason, there are times where you need to decline an invitation. Doing so politely and thoughtfully will ensure that there are no hard feelings.
Decline the invitation in the same way you were originally invited as soon as possible. For example, if you were invited by letter, phone or over the Internet, reply in kind. It is important that you respond in the same way, so you know your message gets through in the manner it was expected. Respond quickly to allow the host to plan the event for an accurate number.
Give a succinct excuse. It's easy to see how not giving an excuse makes you sound thoughtless, but giving an excuse that is too elaborate also will reflect poorly on the invitee. Give a simple, to-the-point excuse that releases you from commitment but doesn't contain too much information.
Fulfil any obligations accepting the invitation may have placed on you. If you were invited to a large event, such as a wedding, baby shower or birthday party, make other arrangements to deliver presents or give well-wishes. This will help you fulfil your social duties without having to attend the actual function.
Thank the person who invited you and express your interest in attending other functions in the future. This will help end your message on a high note and keep you in the person's thoughts in a positive rather than negative way.
Take care not to apologise too much. While a single "I apologize" or "I regret to say" is perfectly fine, saying "sorry" over and over makes you seem disingenuous.