The new rules of saying no to Christmas catch-ups: How to bow out gracefully...
How to bow out gracefully:
Work Christmas dinner
Think about the political message cancelling will send to your boss. If you really can't go (or really don't care), offer to take them for a Christmas drink to make up for it - safe in the knowledge they'll be too busy to take you up on it.
This will have involved hundreds of emails to find a date that suited all of you. If you must pull out, sending some potential dates for the new year, with your apologies, will suggest a degree of sincerity.
Dinner with the in-laws
If they are prospective in-laws then there should be a three-line whip: you absolutely have to be there. If they are relatively new, make sure you tell them yourself, don't leave it to your partner - and arrange to have a bottle of fizz sent to their table.
If you are going over to their place for Christmas Day this year, don't worry - you're sure to pay for it then.
Anyone with a Christmas birthday is already used to having their annual celebrations overshadowed - which only makes it worse if you bow out last-minute. If it's a landmark age, only a face-to-face cancellation will suffice - followed, swiftly, by an extravagant gift.
You'd have to be at death's door to pull out last-minute - your hosts will have made a substantial outlay on your behalf. A phone call is the bare minimum, followed by a hand-written note on top-quality stationery from somewhere such as Smythson (better stock up now).
School carol concert/nativity
It would have to be a career-changing work meeting to miss this: breaking a child's heart is to be avoided at all costs. If it can't be avoided, re-stage the event at home, and invite their friends so they still get a chance to perform for yo