The maximum contribution limit for a Roth 401(k) is determined by the Internal Revenue Service (IRS) and may vary from year to year. As of 2022, the maximum contribution limit for individuals under the age of 50 is $19,500 per year. However, individuals who are 50 years old or older can make catch-up contributions, allowing them to contribute an additional $6,500 per year, for a total maximum contribution of $26,000 per year. It's important to note that these limits are subject to change, so it's always a good idea to consult with a financial advisor or refer to the IRS guidelines for the most up-to-date information.