401(k) after tax limit setup

We are looking for where in the system to put in a 401(k) after tax limit. After tax contributions are limited to 10% of the 401(a)(17) compensation limit established by the IRS.  For 2019 the limit is $28,000. In the past we've had people go over that limit. Now we have a manual process to check it, but wondering what other companies do or if I'm missing something in the system.