The British Cycling Cyclocross age categories for the 2023/24 season are as follows (effective from 1st Sept 2023):

Under 8 born in 2016 or later
Under 10 born in 2014 or 2015
Under 12 born in 2012 or 2013

Youth – born 2008 to 2011
Youth – Under 16 – born 2008 or 2009
Youth – Under 14 born 2010 or 2011

Junior – born 2006 or 2007

Under 23 – born 2002 to 2005

Senior born – 2001 or earlier

Vet 40+ born 1983 or earlier
Vet 40-49 born 1974 to 1983
Vet 40 born 1979 to 1983
Vet 45 born 1974 to 1978

Veteran 50+ born 1973 or earlier
Vet 50 born 1969 to 1973
Vet 55 born 1964 to 1968
Vet 60 born 1959 to 1963
Vet 65 born 1954 to 1958

Vet 70+ born 1953 or earlier