Find Your Extra 401(k) Room
Use this free calculator to estimate your remaining annual 401(k) capacity, then use the checklist and walkthrough to see whether your plan may support a mega backdoor Roth strategy.
Educational resource only. Not financial, tax, or legal advice.
What this page helps with
If you have already maxed your regular employee 401(k) contribution, you may still have additional room inside your plan.
What to verify
Use the checklist to confirm whether your plan allows after-tax contributions and a Roth conversion path.
What to do next
Follow the walkthrough and provider script before making any changes to your plan settings.
Mega Backdoor Roth Capacity Calculator
Enter your numbers below to estimate how much additional after-tax contribution room may remain inside your 401(k) plan.
Estimated Results
Your estimate shows the gap between your current total 401(k) contributions and your plan’s total annual limit. If your plan allows after-tax employee contributions and Roth conversion features, that remaining room may be relevant for a mega backdoor Roth strategy.
Mega Backdoor Roth Eligibility Checklist
Before contributing extra money, confirm these items in your plan documents or with your provider.
Plan feature checks
- My plan allows after-tax employee contributions
- My plan allows in-plan Roth conversions
- Or my plan allows an eligible rollover path for after-tax funds
- My provider tracks contribution sources separately
- I understand how often conversions can be processed
- I know whether conversions can be automated
Personal readiness checks
- I already max my regular employee 401(k) contribution
- I have an emergency fund in place
- I do not have high-interest debt that should be addressed first
- I understand this is an advanced strategy, not a beginner first step
- I am prepared for the reduced take-home pay from after-tax contributions
Step-by-Step Walkthrough
Use this simple process before making changes to your plan.
Find your current contribution totals
Look at your pay stub, provider dashboard, or year-to-date plan summary. Add together your employee contributions and employer contributions.
Estimate your remaining room
Subtract your current total from the total annual plan limit shown in the calculator.
Check your plan features
Review your summary plan description or call your provider to confirm after-tax employee contributions, in-plan Roth conversions, and rollover rules for after-tax funds.
Ask the right questions
Use the provider script below so you can verify the plan features clearly and efficiently.
Review your cash flow
This strategy usually uses after-tax dollars, so make sure your monthly cash flow can support it.
Document everything
Save screenshots, plan responses, and conversion settings so you understand how the process works going forward.
Questions to Ask Your 401(k) Provider
Use these exact questions when you call.
- Does our plan allow non-Roth after-tax employee contributions?
- Does our plan allow in-plan Roth conversions of those contributions?
- Can those conversions be automated?
- How frequently can conversions happen?
- How are after-tax funds tracked separately from other sources?
Call script
“Hi, I’m trying to understand whether my 401(k) plan allows non-Roth after-tax employee contributions and whether those after-tax contributions can be converted through an in-plan Roth conversion or rolled over through an eligible process. Can you tell me what features our plan supports, how often conversions can happen, and whether the contribution sources are tracked separately?”
Watch the Full Breakdown
Watching the YouTube video? This page is the companion resource mentioned in the video. Use the calculator first, then go through the checklist and walkthrough before making changes to your plan settings.
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Want the printable version?
Get the checklist and provider question script in a printable format you can save before your next payroll cycle.
Important Note
This content is for educational purposes only and is not financial, tax, legal, or investment advice. Retirement plan rules vary by employer and provider. Always review your plan documents and consider speaking with a qualified professional before acting.