2026 Mega Backdoor Roth Calculator

Background.

Use 2026 Mega Backdoor Roth Calculator when you need to find remaining annual-additions room after deferrals, employer money and other additions. A mega backdoor Roth depends on a plan allowing after-tax employee contributions and an in-plan Roth conversion or in-service rollover. Here the arithmetic follows “available after-tax room = max(annual-additions limit − employee deferrals − employer contributions − other additions, 0),” rather than silently mixing alternatives.

The editable entries are 2026 annual-additions limit, employee elective deferrals, employer contributions, other annual additions. Use values from the document or measurement that governs this 2026 mega backdoor roth question; the defaults are only the worked fixture below. The most consequential input mistake would be to ignore that the annual-additions limit is not the elective-deferral limit, and plan terms can close the route even when statutory room remains.

IRS Retirement Topics, 401(k) and profit-sharing contribution limits, updated for 2026 documents the convention or governing rule used here. The 2026 mega backdoor roth output is a transparent scenario under those facts: it does not manufacture an unentered market price, professional determination, carrier quote, legal eligibility finding or locally adopted code value.

What is 2026 mega backdoor roth calculator?

2026 Mega Backdoor Roth is the relationship behind this decision: a mega backdoor Roth depends on a plan allowing after-tax employee contributions and an in-plan Roth conversion or in-service rollover. On this page it means available after-tax room = max(annual-additions limit − employee deferrals − employer contributions − other additions, 0). The annual-additions limit is not the elective-deferral limit, and plan terms can close the route even when statutory room remains; that is the line between the reported quantity and a broader retirement analysis.

How to use this calculator.

1. 01Confirm that “available after-tax room = max(annual-additions limit − employee deferrals − employer contributions − other additions, 0)” matches the 2026 mega backdoor roth convention you need.
2. 02Replace the fixture values for 2026 annual-additions limit, employee elective deferrals, employer contributions, other annual additions with dated values from the governing record.
3. 03Keep all currencies, measurement units and time periods on the same basis before calculating.
4. 04Read available after-tax contribution room together with this boundary: The annual-additions limit is not the elective-deferral limit, and plan terms can close the route even when statutory room remains.

The formula.

The calculation uses available after-tax room = max(annual-additions limit − employee deferrals − employer contributions − other additions, 0). In this 2026 mega backdoor roth model, the entered terms are 2026 annual-additions limit, employee elective deferrals, employer contributions, other annual additions. A mega backdoor Roth depends on a plan allowing after-tax employee contributions and an in-plan Roth conversion or in-service rollover, which is why the relationship is presented under this name rather than as a universal alternative. The annual-additions limit is not the elective-deferral limit, and plan terms can close the route even when statutory room remains. Calculations keep full decimal precision through the relationship and round only the returned display values.

A worked example.

Frequently asked questions.

References& sources.

1. [1]IRS Retirement Topics, 401(k) and profit-sharing contribution limits, updated for 2026. Retrieved 2026-08-07. access: open unless marked otherwise.
2. [2]IRS Notice 2025-67, 2026 retirement-plan and IRA limitations. Retrieved 2026-08-07. access: open unless marked otherwise.
3. [3]U.S. Internal Revenue Service. Publication 560, Retirement Plans for Small Business. Retrieved 2026-08-07. independence: primary; access: open.