Coast Retirement · Research · Tax strategy

Backdoor Roth IRA Calculator & Guide for High Earners

Introduction

Backdoor Roth IRA in Plain English

Think of the Roth IRA like a front door with an income limit. If you earn too much, you may not be allowed to walk through by making a direct Roth contribution.

The Backdoor Roth IRA uses a different route:

  1. Contribute to a traditional IRA
  2. Do not deduct the contribution on your tax return
  3. Convert the traditional IRA balance to a Roth IRA
  4. Report the nondeductible contribution and conversion on IRS Form 8606

The contribution is still limited by the regular IRA annual limit. The backdoor does not let you contribute unlimited money to a Roth IRA.

Roth IRAs can be valuable for long-term planning: qualified withdrawals may be tax-free, Roth IRAs have no required minimum distributions for the original owner, and Roth money adds tax flexibility later in life.

At a glance

Your Roth Map by Age and MAGI

Your situation
Sets IRA cap ($7,500 vs $8,600 at 50+).
Modified AGI for Roth IRA limits. What is MAGI?
—
Roth IRA Contribution Route by MAGI and Age
2026 limits · Single / HOH
Direct Roth IRA Contribution
Roth IRA Contribution Phase-Out
Backdoor Roth IRA Route
What Each Zone Means

Three equal bands on the chart (non-linear dollar scale). Thresholds depend on filing status (Single / HOH). IRA limits apply per person, not per household. The map shows which contribution route applies. Pre-tax IRA balances do not change your zone; the calculator below estimates whether a Roth conversion may be taxable.

Direct Roth IRA Contribution

MAGI is below the Roth IRA contribution phase-out start ($153,000). You may contribute the full annual limit directly to a Roth IRA, with no traditional IRA or Roth conversion required.

Up to $7,500 per person per year ($8,600 at age 50+).

Roth IRA Contribution Phase-Out

MAGI is inside the IRS phase-out range ($153,000 to $168,000). Your allowed direct Roth IRA contribution is reduced using the IRS formula below. The remainder of each person’s annual IRA limit is funded through a nondeductible traditional IRA contribution followed by a Roth conversion (often called a backdoor Roth IRA).

Direct portion shrinks as MAGI rises; conversion portion grows. Combined total is still capped at the per-person IRA limit.

Backdoor Roth IRA Route

MAGI is above the phase-out end ($168,000). You may not make a direct Roth IRA contribution. Each eligible person can still use their full IRA limit via:

  1. Nondeductible traditional IRA contribution, an after-tax deposit with no deduction.
  2. Roth conversion, moving that IRA balance to Roth; report on Form 8606.
Phase-Out Split · IRS Formula

Inside the phase-out range only ($153,000 to $168,000 MAGI). From Publication 590-A, Worksheet 2-2. Round direct Roth down to the nearest $10. Direct plus backdoor always equals the IRA limit, never more.

Phase-out start = $153,000 · Phase-out end = $168,000
Direct Roth IRA = IRA limit × (phase-out end − MAGI) ÷ (phase-out end − phase-out start)
Traditional IRA → Roth (backdoor) = IRA limit − direct Roth IRA

Example at $160,500 MAGI: direct Roth IRA $3,750 + backdoor $3,750 = $7,500 total IRA limit.

Both paths use after-tax dollars. Why is there a distinction?

Money in a Roth IRA is ultimately after-tax whether you contribute directly or convert. The IRS still treats them as different transactions:

Direct Roth IRA contribution goes straight into a Roth IRA. One step, no conversion, no Form 8606 for the contribution itself.

Backdoor portion must pass through a traditional IRA first, then a Roth conversion. That triggers IRA aggregation rules: if you hold pre-tax IRA money elsewhere, the pro-rata rule can make part of the conversion taxable even though your new deposit was after-tax. You must file Form 8606, and any earnings before conversion are usually taxable.

The map splits them because the process and tax reporting differ, not because one side is pre-tax and the other is after-tax.

Next: Detailed Calculator

The calculator repeats the same filing status, MAGI, and age from the map. It adds fields the map does not show, because they affect tax on the Roth conversion, not which zone you are in:

  • Pre-tax IRA balance, for pro-rata on conversion (shown on the main form).
  • Form 8606 basis, conversion gain, marginal rate, under Advanced (optional).
Continue to calculator ↓
Calculator

IRA Contribution Calculator

Find your 2026 IRA contribution limit and whether the direct Roth IRA, phase-out, or backdoor route applies. Estimate your numbers or use values from the Roth map above.

Enter Your Information

Complete the fields below, then click Calculate. Limits are per person. Married filing jointly uses combined MAGI for the phase-out only.

Age 50+ adds catch-up ($8,600 vs $7,500).
Same number as the Roth map. What is MAGI?
Traditional, rollover, SEP, and SIMPLE IRA. $0 usually means a cleaner backdoor conversion.
Advanced: pro-rata and conversion tax (optional)
Prior nondeductible IRA contributions on file with the IRS. First backdoor? Leave at $0.
Market gain while waiting to convert. Convert from cash? Use $0.
Guide

How to Use This Calculator

Click Calculate after entering your numbers. The Roth map above syncs filing status, MAGI, and age into the calculator.

  1. Filing status and age, same logic as the Roth map. Age 50+ adds the 2026 catch-up ($8,600 vs $7,500).
  2. MAGI, modified adjusted gross income. See What is MAGI? in the FAQs below.
  3. Pre-tax IRA balance, traditional, rollover, SEP, and SIMPLE IRA. Does not change your zone; affects pro-rata tax on conversion.
  4. Advanced (optional), Form 8606 basis, gain before conversion, and marginal tax rate for a rough conversion tax estimate.
  5. Calculate, shows Roth IRA, traditional IRA → Roth (backdoor), and total IRA contribution. All three add up to the annual limit.

Form 8606, simply: when you file taxes, this form lists how much after-tax money you put into IRAs and how much you converted to Roth, so the IRS knows what was already taxed.

This calculator is a simplified model, not a substitute for a CPA.

Example

Worked Example: Single, $200k, No Existing IRAs

Alex is 35, single, estimates $200,000 MAGI, has no Roth IRA and $0 in any traditional or rollover IRA. Alex maxes a nondeductible contribution and converts a few days later.

InputValue
Filing statusSingle
Age35
MAGI$200,000
Pre-tax IRA$0

Calculator result: which accounts to use this year. Every amount is part of the $7,500 IRA limit.

AccountAmount
Roth IRA (direct)$0
Traditional IRA → Roth IRA (backdoor)$7,500
Total IRA contribution$7,500

At $200,000 MAGI, Alex cannot contribute directly to a Roth IRA. The full 2026 limit goes through the backdoor: nondeductible traditional IRA, then Roth conversion. File Form 8606.

If Alex converts from cash the same day, there is no extra amount beyond $7,500. The Advanced gain before conversion field is only for small market earnings while waiting to convert. That gain is not part of the IRA contribution limit.

Enter these values in the calculator (Single, MAGI $200,000, pre-tax IRA $0) and click Calculate.

Income limits

Why High Earners Should Care

Many high-income professionals can contribute to a 401(k), but cannot contribute directly to a Roth IRA because their income is too high.

For 2026, the IRS limits total annual IRA contributions to $7,500, or $8,600 if you are age 50 or older. Direct Roth IRA eligibility depends on your modified adjusted gross income (MAGI), not gross salary alone. Roth IRA eligibility also phases out at higher income levels:

Filing status2026 Roth IRA direct contribution phase-out
Single / head of household$153,000 – $168,000
Married filing jointly$242,000 – $252,000
Married filing separately$0 – $10,000

If your income is above the direct Roth IRA limit, a Backdoor Roth IRA may be one way to still get money into a Roth IRA. This is especially relevant for:

  • A 35-year-old product manager earning $170,000
  • A 42-year-old married couple earning $260,000 combined
  • A 50-year-old executive who already maxes a 401(k) and wants tax diversification
  • A Gen X household balancing kids, mortgage, aging parents, and career risk
Critical warning

The Biggest Mistake: The Pro-Rata Rule

If you have both after-tax IRA money and pre-tax IRA money, the IRS generally treats your conversion as coming proportionally from both buckets. You cannot simply say, “I only converted the after-tax dollars.”

Simple pro-rata example

Assume you have:

  • $7,500 nondeductible traditional IRA contribution
  • $92,500 existing pre-tax IRA money
  • $100,000 total traditional IRA balance

Your after-tax basis is only 7.5% of the total IRA balance. If you convert $7,500, only about 7.5% of that conversion may be treated as nontaxable. The rest may be taxable.

That is why a Backdoor Roth IRA is often cleanest when your traditional IRA, SEP IRA, and SIMPLE IRA balances are zero at year-end.

Nontaxable percentage = after-tax IRA basis ÷ total IRA value
Taxable amount = conversion amount − nontaxable portion

This is simplified. The actual calculation belongs on Form 8606 and depends on your year-end IRA balances, distributions, conversions, and basis.

Fit

When a Backdoor Roth IRA May Make Sense

  • Your income is too high for a direct Roth IRA contribution
  • You already max your 401(k), or at least get the full employer match
  • You want more tax-free retirement money later
  • You have no pre-tax traditional IRA, SEP IRA, or SIMPLE IRA balances
  • You can keep good tax records and file Form 8606 correctly
  • You are building flexibility for early retirement, Coast FIRE, or future Roth conversion planning
Fit

When a Backdoor Roth IRA May Not Be Worth It

  • You already qualify for a direct Roth IRA contribution
  • You have large pre-tax IRA balances and do not understand the pro-rata rule
  • You need the money soon
  • You have high-interest debt and no emergency fund
  • You are not contributing enough to get your 401(k) match
  • Your tax situation is complicated and you do not have help
  • You are using the Roth IRA as a short-term trading account

For many high earners, the Backdoor Roth IRA is a useful extra step after the basics are handled, not a substitute for the bigger retirement picture.

Priorities

Where It Fits in the High-Earner Retirement Order

A common order of operations for a high-income household:

  1. Build a real emergency fund
  2. Get the full 401(k) employer match
  3. Pay off high-interest debt
  4. Consider HSA contributions if eligible
  5. Increase 401(k) contributions
  6. Consider Backdoor Roth IRA if direct Roth is not available
  7. Build taxable brokerage savings
  8. Consider 529 plans, mortgage payoff, real estate, or other goals

The right order depends on your household. That is why the Backdoor Roth should connect to a full retirement model, not just a tax hack.

Run your numbers in the full planner →

Checklist

Backdoor Roth IRA Checklist

Before Contributing

During the Process

At Tax Time

FAQs

What is MAGI and how do I estimate it?

MAGI is your adjusted gross income (AGI) plus certain deductions the IRS adds back for Roth IRA eligibility. Find AGI on line 11 of Form 1040. MAGI itself is not on your tax forms. For Roth purposes, common add-backs include student loan interest deducted, a traditional IRA deduction you claimed, and foreign earned income excluded. Many W-2 earners without those items find MAGI close to AGI. For planning, estimate wages, bonus, RSU income, and other taxable income you expect this year, or use last year's AGI as a starting point. See IRS Publication 590-A for the full Roth MAGI worksheet.

What is the difference between a traditional IRA and a Roth IRA?

A traditional IRA often gives you a tax deduction when you contribute (if you are eligible), but withdrawals in retirement are generally taxable. A Roth IRA uses after-tax contributions, no deduction upfront, but qualified withdrawals in retirement are generally tax-free. Direct Roth contributions have income limits; traditional IRA contributions do not, though deductibility can phase out at higher incomes. A backdoor Roth starts with a traditional IRA contribution, then converts to Roth.

Is a Backdoor Roth IRA legal?

The IRS provides rules for nondeductible traditional IRA contributions, Roth conversions, and Form 8606 reporting. The strategy depends on following those rules correctly. It is not a separate IRS account type.

Is there an income limit for a Backdoor Roth IRA?

The direct Roth IRA contribution has income limits. The Backdoor Roth IRA strategy is used because of those limits. However, the regular annual IRA contribution limit still applies, and you need taxable compensation.

Does the Backdoor Roth IRA avoid taxes?

Not exactly. If done cleanly with after-tax money and no pre-tax IRA balances, the conversion may create little or no tax beyond any earnings before conversion. But if you have pre-tax IRA money, the pro-rata rule can make much of the conversion taxable.

What is Form 8606?

Form 8606 reports nondeductible traditional IRA contributions, distributions involving basis, and Roth conversions. It is the form that helps track money that was already taxed.

What if I don't know whether I filed Form 8606?

You do not receive Form 8606 in the mail like a W-2. You or your tax preparer file it with your federal return when you make nondeductible IRA contributions, take certain IRA distributions, or do a Roth conversion. Check past tax returns for Form 8606 (and related amounts on Schedule 1). If you made after-tax IRA contributions in earlier years but never filed it, your basis may not be documented with the IRS. A tax professional can help you reconstruct records before you convert. When you do a backdoor Roth, plan to file Form 8606 for that tax year.

What is the pro-rata rule?

The pro-rata rule means that if your IRA money includes both pre-tax and after-tax amounts, a conversion is generally treated as coming proportionally from both. You usually cannot choose to convert only the after-tax dollars.

Should I do the conversion immediately?

Many people convert soon after the traditional IRA contribution settles to reduce taxable earnings before conversion. Timing can vary by custodian and personal tax situation.

What if I have an old rollover IRA?

Be careful. A rollover IRA with pre-tax money can trigger the pro-rata rule. Before doing a Backdoor Roth IRA, review whether that balance can be moved into a current employer plan, converted intentionally, or left alone.

Can my spouse do a Backdoor Roth IRA too?

Potentially yes, if the spouse is eligible. IRA contribution limits apply per person, but each spouse's IRA balances and tax reporting need to be handled correctly.

Is a Backdoor Roth IRA better than a taxable brokerage account?

Not always. A taxable brokerage account has flexibility and no retirement account contribution limit. A Roth IRA has tax advantages but more rules. High earners often use both.

Should I do a Backdoor Roth IRA before maxing my 401(k)?

Usually the 401(k) match comes first. After that, the order depends on taxes, fees, plan quality, cash flow, and goals. Use the full Coast Retirement Planner to see how each account type fits into your future withdrawals.

* Educational only, not tax advice. Backdoor Roth IRA rules are tax-sensitive, and a mistake can create unexpected income taxes. Talk with a qualified tax professional before implementing.

CoastRetirement.com provides educational calculators and planning models. It does not provide individualized financial, investment, tax, or legal advice. Calculator outputs depend on user-provided assumptions and are not guarantees of future results.

Sources (last reviewed 2026-06-15): IRS: 2026 401(k) and IRA limits · IRA contribution limits · Form 8606 · Publication 590-A · Publication 590-B