PMFJI, but your example failed also, when you change the year, because of the leap year problem. I tried to change the year to the year that was stated in the begining of the thread (2018), and the date came back empty. So it is not fool-proof.

>Sergey, the second is simpler,faster and it is the only solution;
>the first can fail:
>

>dob=DATE(2000,2,29)
>? DATE(YEAR(dob)-100, MONTH(dob), DAY(dob))
>? GOMONT(dob, -100*12)
>