Depending on who you are writing to, you can use these templates from sources like Preply and The Intrepid Guide: :
"Le auguro un felice compleanno." (I wish you a happy birthday — using the formal 'Le'.) . : "Auguri in ritardo!" (Happy belated birthday!) . Creative Birthday Cards gli_auguri_di_buon_compleanno_perfetti
"Ti auguro di raggiungere tutti i tuoi obiettivi!" (I wish you to reach all your goals!) . Depending on who you are writing to, you
: Literally "Many wishes," this is the most common and versatile way to celebrate any special occasion. gli_auguri_di_buon_compleanno_perfetti