The maximum Roth 401(k) contribution for 2019 was $19,000 plus, for those over age 50 in 2019, a $6,000 catch-up; it's too late to contribute for 2019 unless you are self-employed and before the end of 2019 you made the election to make the Roth contribution. For 2020 it's $19,500 plus a $6,500 catch-up.
