Every so often, praise is deserved. This is where you can give recognition for hard work and achievement. Whether it's a promotion, or just good work, you can always improve staff morale with some positive feedback.
The basic letter is simple enough, but it should be personalized. The letter should use your own personal style, to show that it's a real letter from you to the staff member, not another business form.
The letter format
Use a business letterhead, with a file reference to the staff member's personal file, and an original signature.
File HR 1294
Dear… First name of staff member
Re: Your new promotion
Congratulations on your promotion to (job title)! Good to see that all your hard work over the years has been rewarded. Your promotion is thoroughly deserved, and it's a real pleasure to see your commitment and experience getting its proper recognition.