What it is
A designated Roth 401(k) account is a source within an employer plan, funded with after-tax deferrals. It is not a Roth IRA even though both use the word Roth.
Why it exists
It lets eligible plan participants choose different tax timing for payroll saving while keeping the employer plan’s investment menu and administration.
When it may help
It may help when identifying which portion of a workplace balance is Roth and which is pre-tax, or reviewing an employer’s current contribution options.
When it may not fit
It does not provide a current deduction for Roth deferrals and should not be assumed to follow Roth IRA withdrawal ordering or direct-contribution eligibility rules.
Tradeoffs and access
Plan restrictions, investment costs and distribution eligibility still apply. A plan may offer in-plan conversions, but that is a separate feature and decision. Employer contribution treatment must be checked rather than inferred from the employee’s election.
Tax considerations
Qualified designated Roth distributions can be tax-free under holding-period and qualifying-event rules. Nonqualified distributions can include taxable earnings. Current annual deferral and catch-up requirements should be verified with the administrator.
Common mistakes
Do not treat choosing Roth for future pay as automatically converting an old pre-tax balance. Do not label every employer contribution Roth without confirmation.
Fictional example
Fictional Lee changes future payroll deferrals to Roth but still has an older pre-tax balance. Lee records the two sources and their tax questions separately.
Questions to ask
Which contribution sources exist? What date starts the relevant holding period? Does the plan allow conversions? Which distribution and rollover choices apply?
What to record in Planstead
Record the plan and reported tax treatment in Retirement & Pensions with a dated statement reference. Keep the full balance from being counted twice.
Next step
Request the plan’s Roth explanation and latest source breakdown before making a contribution or distribution election.
Sources
Primary sources reviewed 2026-09-14. A source describes its own rules; the fictional examples illustrate questions, not a recommendation.