<prompt> Human: I am only able to set a percentage based contribution but due to variable income holiday pay, target bonuses... its generally the same every 2 weeks but towards the end of the year can start to get a lot different Im not sure what the best way to manage it would be. Should I try my best to get just short of the 18,500 max and then for the last paycheck do my best to guess exact percentage? Or should I just go over and deal with the consequences. What are the consequences of going over?  <response>: In general, most payroll systems will automatically cut off 401K deferrals once you reach the limit which this year is 18,500, so you shouldnt have to worry about going over.The one thing you might have to worry about is missing out on matching funds if your employer matches contributions on a per-paycheck basis. Some employers will perform true-up matching if you hit the max early in the year, but some dont. This also isnt a problem if your employer doesnt match contributions instead doing flat contributions, or no contributions at all.I would set your deferral percentage to 18500 divided by expected yearly salary round up if they dont allow decimal rates, then check your deferral progress quarterly, making adjustments if your actual deferrals are above or below your target. 