The Four Doors Into a Roth (and the Tripwire on Each)

People say “Roth” like it’s one thing. It isn’t. There are four different ways to get money into a Roth account, and they run from dead simple to genuinely advanced. The contribution limits are different for each, the income rules are different for each, and every one of them has a tripwire that turns a smart move into a tax bill if you miss a step. Here’s the ladder, bottom to top.

Door 1: The Roth IRA

The front door. You contribute after-tax dollars, the money grows tax-free, and qualified withdrawals in retirement come out tax-free. For 2026 you can put in $7,500, or $8,600 if you’re 50 or older (that’s a $1,100 catch-up).

The catch is income. Once your modified income climbs past the phase-out range — $153,000 to $168,000 for single filers, $242,000 to $252,000 for married filing jointly — the front door closes. Above the top number, you can’t contribute directly at all. You also need earned income to contribute in the first place.

Door 2: The Roth 401(k)

A bigger door, opened through your employer’s plan (or your own solo 401(k)). Same deal — after-tax in, tax-free out — but the limits are far higher: $24,500 in 2026, plus an $8,000 catch-up at 50+, and a $11,250 “super catch-up” for ages 60 through 63 that pushes those four years up to $35,750.

Here’s the part people miss: the Roth 401(k) has no income limit. Earn $400,000 and you can still fund it. That’s the key difference from the Roth IRA. One new rule for 2026 — if your prior-year Social Security wages topped $150,000, your catch-up contributions have to go in as Roth whether you like it or not.

If you’re an S-corp owner, your contribution room here is built on your W-2 wages — which is one more reason your reasonable salary isn’t a number to guess at.

Door 3: The backdoor Roth

This is for high earners locked out of Door 1. There’s no income limit on Roth conversions — only on contributions — so the move is: put $7,500 into a nondeductible traditional IRA, then convert it to Roth. Same $7,500 lands in the Roth, income limit sidestepped.

Two tripwires. First, the pro-rata rule: the IRS looks at all your traditional, SEP, and SIMPLE IRA balances combined. If you’ve got pre-tax money sitting in any of them, you can’t just convert the after-tax piece — the conversion gets taxed proportionally. A $7,500 backdoor when you already hold $92,500 of pre-tax IRA money is roughly 93% taxable. Second, you have to file Form 8606 to record the basis, or you’ll end up taxed twice on the same dollars.

Door 4: The mega backdoor Roth

The big one — and the one most plans don’t allow, so check before you count on it. It only works if your 401(k) permits after-tax (non-Roth) contributions plus either in-plan Roth conversions or in-service withdrawals.

The math runs off the total 401(k) cap. For 2026, everything that goes into the plan — your deferral, the employer match, and after-tax money — is capped at $72,000. Say you put in your $24,500 and your employer adds $10,000; that’s $34,500. The remaining $37,500 can go in as after-tax dollars and be converted straight to Roth. That dwarfs the $7,500 a regular IRA allows, and solo 401(k) owners can have a plan built to permit it.

How to actually climb it

Fill the front doors before reaching for the back ones. Max your Roth IRA and Roth 401(k) first — they’re simple and bulletproof. The backdoor and mega backdoor are for people who’ve already done that and still have money to put away. Just don’t skip the fine print: the pro-rata rule, the 8606, a plan that doesn’t allow after-tax contributions. Each one is a small detail that costs real money when it’s missed.

This article is general information, not tax, legal, or investment advice. Contribution limits, income phase-outs, and the right funding order depend on your income, your plan, and your existing IRA balances — let's look at your specific situation before you contribute or convert.