This sample rejection letter wishes the recipient a happy birthday while declining to attend their birthday party.
Free to download and print.
Dear {Name},
Thank you so much for inviting me to your party! {Age number}, that's exciting! I really wish I could attend, but I'm afraid I'm not available on {date}. I hope that your birthday is a joyous affair, and I'd love to hang out soon and buy you a celebratory lunch.
Warmly,
{Name}