In my 24yrs, the only time I had my birthday off was when it fell on a weekend, or in a vacation week I had scheduled.
Granted, I was hired when we still used wet clay tablets and used sticks to impress the shipper numbers in cuneiform, so my info might be dated.
Way back then, not one minute counted to full hire after the cutoff date for seasonal hire.
Buy yourself a birthday gift with the money you earn on Dec. 20.