Not true. My son is a November 1999 and is a 2017.
Some time back, BOTC created a complete table of birth dates, graduation classes, school grades, and the corresponding U/age groups. The cut-off date for school enrollment is December 1st and the cut-off date for U/age groups is August 31st in this table (different from the July 31st cut-off date used in Youth Soccer but consistent with US Lacrosse).
Based on this data, a November 1999 birth date is a Class of 2017 graduate (one of the youngest in their 8th grade) and a U/13 player, one of the oldest in that age group. (Note that this DOES NOT account for late starting in school or being held back which we assume was not the case for our poster.)
It is very important that readers look at this data since those October/November birthdates tend to create most of the controversy and this example helps you to see why!
12/01/94 - 08/31/95 ... Class of 2013 ... 12th Grade ... U/18 09/01/95 - 11/30/95 ... Class of 2013 ... 12th Grade ... U/17
12/01/95 - 08/31/96 ... Class of 2014 ... 11th Grade ... U/17 09/01/96 - 11/30/96 ... Class of 2014 ... 11th Grade ... U/16
12/01/96 - 08/31/97 ... Class of 2015 ... 10th Grade ... U/16 09/01/97 - 11/30/97 ... Class of 2015 ... 10th Grade ... U/15
12/01/97 - 08/31/98 ... Class of 2016 ... 9th Grade .... U/15 09/01/98 - 11/30/98 ... Class of 2016 ... 9th Grade .... U/14
12/01/98 - 08/31/99 ... Class of 2017 ... 8th Grade .... U/14 09/01/99 - 11/30/99 ... Class of 2017 ... 8th Grade .... U/13
12/01/99 - 08/31/00 ... Class of 2018 ... 7th Grade .... U/13 09/01/00 - 11/30/00 ... Class of 2018 ... 7th Grade .... U/12
12/01/00 - 08/31/01 ... Class of 2019 ... 6th Grade .... U/12 09/01/01 - 11/30/01 ... Class of 2019 ... 6th Grade .... U/11
12/01/01 - 08/31/02 ... Class of 2020 ... 5th Grade .... U/11 09/01/02 - 11/30/02 ... Class of 2020 ... 5th Grade .... U/10
12/01/02 - 08/31/03 ... Class of 2021 ... 4th Grade .... U/10 09/01/03 - 11/30/03 ... Class of 2021 ... 4th Grade .... U/9
12/01/03 - 08/31/04 ... Class of 2022 ... 3rd Grade .... U/9 09/01/04 - 11/30/04 ... Class of 2022 ... 3rd Grade .... U/8
12/01/04 - 08/31/05 ... Class of 2023 ... 2nd Grade .... U/8 09/01/05 - 11/30/05 ... Class of 2023 ... 2nd Grade .... U/7