The Backdoor Roth IRA: A Step-by-Step Guide for High Earners

Why This Exists

Direct Roth IRA contributions phase out at higher incomes ($150k–$165k single, $236k–$246k married filing jointly in 2026). Above those, you can't contribute directly.

But there's no income limit on Traditional IRA contributions, and there's no income limit on converting a Traditional IRA to a Roth. Chain those two together and you get a "backdoor" Roth contribution. Congress explicitly blessed the strategy in 2018.

The 4-Step Process

Step 1: Open a Traditional IRA at any major brokerage (Fidelity, Schwab, Vanguard). If you already have one with pre-tax money in it, stop and read the pro-rata section below first.

Step 2: Contribute the annual limit — $7,000 in 2026, or $8,000 if you're 50+. Contribute after-tax money and do not deduct it on your tax return. Leave it in cash, don't invest yet.

Step 3: Convert to Roth IRA. Wait 1 day (Vanguard) to 1 week (some brokerages recommend it, though the IRS has no waiting rule). Then convert the entire Traditional IRA balance to a Roth IRA. Same brokerage, one form.

Step 4: Invest inside the Roth. Now buy your S&P 500 index fund or whatever your plan calls for. Any growth from here is tax-free forever.

Step 5 (at tax time): File Form 8606 to document the non-deductible contribution and the conversion. Miss this form and the IRS will try to tax you twice. Every DIY tax software (TurboTax, FreeTaxUSA) handles it once you check the right boxes.

The Pro-Rata Rule (The One Big Trap)

If you have any pre-tax money in any Traditional IRA, SEP-IRA, or SIMPLE IRA on December 31 of the conversion year, the IRS treats a portion of your conversion as pre-tax — creating a surprise tax bill.

Example: $50,000 pre-tax rollover IRA + $7,000 new after-tax contribution = 87.7% of your conversion is taxable.

Fixes before doing a backdoor Roth:

1. Roll pre-tax IRA money into your current employer's 401(k) if the plan accepts rollovers. This makes the balance $0 for pro-rata purposes.
2. Convert the pre-tax IRA to Roth in full and pay the tax bill (only if it's small and you're in a low bracket).
3. Skip the backdoor Roth entirely and use a taxable brokerage instead.

401(k) balances don't count toward pro-rata — only IRAs.

Mega Backdoor Roth (Bonus)

If your 401(k) allows after-tax contributions and in-service Roth conversions, you can shove another $30,000–$40,000/year into Roth via the "mega backdoor." Check your Summary Plan Description for "after-tax contributions" (not to be confused with Roth 401(k) contributions).

If you have this option, use it aggressively — it's the most powerful legal tax shelter for W-2 earners.

When It's Worth It

• You're already maxing your 401(k) to the $24,000 employee limit.
• You're maxing your HSA.
• Your income disqualifies you from direct Roth contributions.
• You have $0 pre-tax IRA balance (or you're willing to fix it).

If any of those is a "no," start there first — see the priority order in the 401(k) contribution guide.

Model the Payoff

$7,000/year for 30 years at 8% is ~$856,000 — all tax-free. Compare that in the compound interest calculator with your taxable brokerage alternative and the backdoor Roth wins by six figures every time.