Project a Roth balance built with recurring after-tax workplace-plan contributions and translate the projected balance into an annual income target. This Mega Backdoor Roth income estimator is designed for long-horizon scenario planning when a plan permits after-tax contributions and Roth conversion or rollover mechanics. It compounds a starting balance plus a recurring annual amount, then applies your chosen withdrawal percentage. It does not enforce plan-specific contribution ceilings, test eligibility, or determine whether future distributions satisfy tax-free qualification rules.
1. Enter an existing Roth balance
Include any starting amount you want in the projection.
2. Add the annual after-tax amount
Keep the amount within your employer plan's actual rules and applicable limits.
3. Choose the accumulation period
Set how long the recurring amount will be added.
4. Set growth and withdrawal rates
Use consistent scenario assumptions when comparing strategies.
5. Review annual and monthly income
These figures are percentage-of-balance estimates, not guaranteed payments.
The model assumes the annual amount is added before each year's growth and that conversions are completed without reducing the invested contribution for taxes.
For 2026, the IRS annual-additions limit for defined-contribution plans is $72,000 before applicable catch-up contributions, but employer contributions and plan rules affect the room actually available for after-tax contributions.
The result shows a first-year income target calculated from the projected Roth balance and your selected withdrawal percentage.
A Mega Backdoor Roth is plan-dependent; confirm operational steps and limits before treating an annual contribution assumption as available capacity.
Given
Calculation
Repeat B(t+1) = (B(t) + $25,000) × 1.06 for 15 years, then multiply the resulting balance by 4%.
Result
Projected balance is about $976,297 and first-year estimated income is about $39,052, or about $3,254 per month.
This is a planning conversion from wealth to income; it does not specify an optimal or safe withdrawal rate.
No. Enter only the after-tax amount you believe is available. The IRS elective-deferral limit and the broader annual-additions limit are different constraints.
Employer contributions generally use part of the annual-additions limit, which can reduce space available for after-tax employee contributions. This calculator does not compute that remaining space.
No. It is simply annual estimated income divided by 12 for planning.
Yes. Enter zero and the projection will be built only from the recurring annual amount.
No. It assumes the full entered after-tax amount reaches the Roth path. Earnings that accumulate before conversion can create taxable income and should be modeled separately.