Age on Birth Certificate

[WalsallRobbo]

I have just got the birth certificate back for my daughter, born on 8/9/18.

I was born in November 1977, making me 40, but on the certificate it states that I am 41.

My wife was born in July 1978 but on the certificate it states that she is 40.

Do you know why this would be the case? 

[Just Weird]

2018 is your 41st year, 2018 is your wife's 40th year. 

[WalsallRobbo]

Thanks very much - that explains it.