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What is a mega backdoor Roth?

A mega backdoor Roth is a strategy where you make after-tax contributions to your 401(k) beyond the normal employee deferral limit, then convert those dollars to Roth. It can move a substantial amount into tax-free growth each year, but only if your specific plan permits both after-tax contributions and Roth conversions.

How it differs from the regular backdoor Roth

The regular backdoor Roth moves a comparatively small amount through a traditional IRA each year. The mega version runs through your workplace 401(k) instead, and the ceiling is the overall annual additions limit the IRS sets for all contributions to your plan, which is several times larger. Same destination, much bigger door.

The three things your plan has to allow

First, after-tax contributions, which are a separate category from your pre-tax and Roth deferrals and are easy to confuse with them. Second, a way to get those dollars into Roth, either an in-plan Roth conversion or in-service withdrawals to a Roth IRA. Third, enough room under the annual additions limit after your own deferrals and the employer match. Plenty of plans allow none of this, and the only way to know is to read the plan document or ask.

Why the timing of the conversion matters

After-tax dollars are already taxed, but any earnings they generate before conversion are not. Convert quickly and there is little growth to tax. Let after-tax money sit for a year first and you may owe income tax on the earnings when you convert. Plans that offer automatic or daily conversion make this close to frictionless. Plans that require a phone call each time reward being organized.

The honest limits

This is a high-income strategy that assumes you are already maxing your regular deferral and still have cash to save. It also assumes your plan cooperates. If it does not, the ordinary answers still work: max the deferral, use an HSA if you qualify, and invest the rest tax-efficiently in a taxable account. A mega backdoor Roth is a very good tool, not a prerequisite for a good plan.

How this works at Hunt Wealth

We read your actual plan document to see which of the three requirements your employer meets, then build the contribution sequence into your cash-flow plan so the after-tax dollars go in and get converted on schedule instead of by memory.

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