Split between pretax and Roth when employee about to max out

If the employee about to max out at 402g, let's say he contributed $20k, and still have$500 left. and his original contribution % is 10% pretax and 5% Roth. Either 10% pretax and 5%Roth will over $500. How should payroll to set up split this $500? Weight average? or evenly?

If the plan does not specify a hierarchy I would think prorated/weighted split is most reasonable. So $500 would be $333.33 pre-tax and $166.67 Roth, +/- a penny on either side depending on how you round.

Consistent administrative procedure should be set up. Any method seems like it would be acceptable as long as it is consistent. The pay roll probably has a hierarchy established. I had that happen to someone this year and their payroll which did ROTH first which capped him out and he had no traditional on his final deposit.