You have the option to convert all or a portion of your non-Roth 401(k) account balances to a Roth 401(k) account within the Plan (the number of in-plan conversions is not limited). When making an in-plan conversion, you will owe taxes on before-tax amounts you convert that year. Thereafter, your Roth 401(k) account — including any investment earnings — is tax-free if you meet the Roth distribution requirements.