<prompt> Human: I contribute to my 401k through my companys plan, but I do it as a percentage of my bi-monthly paycheck. If I were to exceed the maximum by the end of the year, what would happen? Would they simply stop withdrawing from my paycheck, or would I somehow be penalized for any overage that I allocated? Is there any chance that I am just losing this money entirely? As a secondary question, what happens if I reach a point mid-year salary wise that prohibits me from contributing to a Roth IRA? Would I be automatically prevented from depositing, or would I receive notice at some point next year?Thanks in advance.  <response>: If I were to exceed the maximum by the end of the year, what would happen?Under most plan documents, the company is supposed to stop taking payroll reductions once you hit the limit.If the company misses it and takes out too much, the administrator is supposed to catch it and refund it to you with any earnings by the following April 15. You report it on your tax return for the contribution year but not for the refund year.If the employer fails to correct the excess deferral by April 15 of the following year, then there is double tax. The employee gets no deduction for the excess deferral in year 1 and will be taxed on the refunded amount in year 2, meaning the same dollars are taxed twice. Theres no IRS relief for taxpayers if this happens. 