My company caps you at 20% of BASE salary, and being in sales only 45% of my comp plan is base salary.
They had one loophole that stated, if you contribute 20% all year, you can do a "catch up" in Nov/December and go up to 100% (minus FICA, health, dental, etc). So I was able to get pretty darn close in 2015, 2016, and now 2017. Thanks to a promotion taking my base salary to $90k/yr, 2018 will be my first year being able to really max it out.
I will be 31 years old.