The maximum contribution limit for a Roth 401(k) is determined by the IRS and can change annually. As of 2024, the maximum contribution limit for individuals under the age of 50 is $20,500, while individuals aged 50 and over can make an additional catch-up contribution of $6,500, bringing their total maximum contribution to $27,000. It's important to note that these limits are subject to change, so it's advisable to stay updated with the latest IRS guidelines and consult with a financial advisor for personalized advice on retirement contributions and planning.