Your last paycheck was bigger than usual, and that came as a surprise. You learn that your boss cut you a handsome slice of this month's bonus budget, and you'd like to show your gratitude. Money is always a delicate subject, but there's a way to do this right: Thanking a boss for a bonus is a matter of sincerity, tact and style.
Make sure it's appropriate to write a thank-you note. If your boss gave you a bonus out of sheer generosity or special acknowledgement of work you've done, go ahead. But if the bonus is part of your normal salary, thanking your boss might come across as awkward. You don't thank your boss for your normal paycheck, so there's no reason to give special thanks for a pre-negotiated quarterly bonus, either.
Write out a thank-you note by hand. Pre-written greeting cards are OK, and typewritten notes are too, but a handwritten, from-the-heart thank-you note will stand out.
Compose your message. Write this just like a short letter. Use your boss' first name, or a courtesy title and last name--whichever your boss prefers. Offer thanks, but not in great detail; "Thanks for your generous gesture during our most recent pay period" is better than "I really appreciated the extra 50 bucks."
Look to the future. Use the opportunity to make another good impression: "I truly enjoy working here, and I appreciate your kindness and support."
Sign the card. Use a closing such as "Best," "Regards" or "Sincerely." If it's a small company and your boss calls you by your first name, use your first name. If not, use your full name.
Seal the envelope, stamp it and address it to your boss at work. Send the letter from home; it shows you took the trouble to do this on your own time and in a personal way.