I'm so sorry I forgot your birthday. The good news is that if you forget mine next year I'll forgive you. Happy Belated Birthday!

I'm so sorry I forgot your birthday. The good news is that I also forgot your age. Happy belated Birthday!

Sorry I missed your birthday by several days, but happy birthday anyways!

Happy Birthday! Don't think of this as a late birthday card. Consider it a very early one for next year. Here's wishing you a wonderful year ahead!

I know you think this card is a few days late. It's actually worse than that. This is your card from 2010 that I only just got around to sending. Happy Belated Birthday!

Dear [name], HBBD! That stands for Happy Belated Birthday! Love, YTDF (Your Terribly Disorganized Friend)

I promise this card isn't late. It is intentionally arriving after your birth-day, because I think you deserve a whole birth-month. Happy Birth-month!

Now that everyone else's birthday wishes have worn off, here's a great big one from me!

Happy belated Birthday! I'm so sorry I forgot to write earlier, but how do you expect me to remember your birthday if you never look any older?

Wishing you many blessings on your special day. We miss you! We hope you have a wonderful birthday and look forward to seeing you at [insert month, or event eg. Christmas].

Wishing you many happy returns on your special day! Sending all our love from [insert location]. We miss you!