How to Calculate Your Roth IRA Contributions and MAGI

To calculate a Roth IRA contribution for 2026, start with the base limit of $7,500 (or $8,600 if you’re 50 or older), then check whether your modified adjusted gross income (MAGI) falls below, inside, or above the phase-out range for your filing status. Below the range, you can contribute the full amount. Above it, you can’t contribute at all. Inside it, you run a reduction formula to find your allowed amount.1Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500

The Three Numbers You Need Before You Calculate

Three inputs drive the entire calculation: your age, your filing status, and your MAGI. Age tells you whether the catch-up applies. The 2026 base limit is $7,500 for anyone under 50, and $8,600 (base plus a $1,100 catch-up) for anyone 50 or older. There is no enhanced “super catch-up” for IRAs; that provision applies only to employer plans like 401(k)s.1Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026, IRA Limit Increases to $7,500

Filing status sets the income thresholds you compare your MAGI against:

MAGI is the figure you compare against those thresholds. It’s calculated below.

How to Find Your MAGI

Start with the adjusted gross income on line 11 of your Form 1040, then add back certain items: student loan interest deductions, tuition deductions, foreign earned income exclusions, and a few other adjustments. For most W-2 employees without foreign income, MAGI and AGI are the same number.

Married filing jointly means combining both spouses’ income into a single MAGI. If you’re planning a contribution partway through the year, last year’s return gives you a reasonable estimate. You have until the tax filing deadline (typically April 15 of the following year) to make or adjust a contribution for a given tax year, so there’s room to fine-tune once your actual numbers come in.

Running the Phase-Out Reduction

If your MAGI lands inside the phase-out range, your contribution shrinks on a straight-line basis. The steps:

  1. Subtract the lower threshold from your MAGI.
  2. Divide the result by the width of the phase-out range: $15,000 for single or head of household, $10,000 for married filing jointly, $10,000 for married filing separately.
  3. Multiply that fraction by the maximum contribution for your age. This is the reduction amount.
  4. Subtract the reduction from the maximum. That’s your allowed contribution.3Office of the Law Revision Counsel. 26 USC 408A – Roth IRAs

A worked example. You’re a single filer, age 40, with a 2026 MAGI of $160,000.

  • Step 1: $160,000 − $153,000 = $7,000
  • Step 2: $7,000 ÷ $15,000 = 0.4667
  • Step 3: $7,500 × 0.4667 = $3,500 (reduction)
  • Step 4: $7,500 − $3,500 = $4,000 (allowed contribution)

If you were 52 with the same MAGI, you’d apply the same 0.4667 ratio to the $8,600 limit. That produces a reduction of roughly $4,013 and an allowed contribution of $4,587, which rounds up to $4,590. The IRS rounds the reduced amount up to the next $10, and the contribution floor never drops below $200 until the phase-out ends eligibility entirely.

Getting this wrong is not just a math problem. Contributing more than your allowed amount triggers a 6% excise tax on the excess for each year it stays in the account.4Office of the Law Revision Counsel. 26 USC 4973 – Tax on Excess Contributions to Certain Tax-Favored Accounts and Annuities

The Compensation Ceiling

One requirement sits above the phase-out math: your contribution can’t exceed your taxable compensation for the year. Taxable compensation means wages, salaries, and self-employment income. Investment income and rental income don’t count. If your taxable compensation for 2026 is $4,000, that’s the most you can contribute, even if the phase-out would otherwise allow the full $7,500.5Internal Revenue Service. Retirement Topics – IRA Contribution Limits

Your final allowed contribution is the smaller of your phase-out result and your taxable compensation.

Spousal Contributions on One Income

Married filing jointly gets a workaround for a spouse with little or no earnings. The working spouse’s compensation can support contributions for both, so each spouse can contribute up to $7,500 (or $8,600 if 50 or older), provided the couple’s combined contributions don’t exceed their joint taxable compensation.5Internal Revenue Service. Retirement Topics – IRA Contribution Limits The married-filing-jointly phase-out still applies to the couple’s MAGI, and each spouse needs their own separate Roth IRA account.

Fixing an Excess Contribution

If your calculation was off and you contributed too much, you can avoid the 6% penalty by withdrawing the excess amount plus its earnings before your tax filing deadline, including extensions.6Internal Revenue Service. IRA Year-End Reminders You can’t just pull out the extra dollars. You also have to withdraw the net income attributable (NIA) to that excess.

The NIA formula is:

Net Income = Excess Contribution × (Adjusted Closing Balance − Adjusted Opening Balance) ÷ Adjusted Opening Balance7eCFR. 26 CFR 1.408-11 – Net Income Calculation for Returned or Recharacterized IRA Contributions

The adjusted opening balance is the account value at the start of the computation period plus any contributions made during it (including the excess). The adjusted closing balance is the account value at the end of the period plus any distributions made during it. If the account lost value, the NIA is negative and you withdraw less than the excess amount. Most IRA custodians will run this calculation for you, but knowing the formula helps you catch errors.

When Your Income Is Over the Limit

If your MAGI is above the upper end of your phase-out range, direct Roth contributions are off the table for that year. A “backdoor” conversion is a separate path: contribute to a traditional IRA (no income limit applies to nondeductible contributions) and convert those funds to a Roth. The calculation there is different because the pro-rata rule pulls all your traditional, SEP, and SIMPLE IRA balances into a single pool when determining the taxable portion of the conversion.8Internal Revenue Service. Instructions for Form 8606

The nontaxable share of the conversion equals your after-tax IRA basis divided by your total traditional-IRA balance across all such accounts. If you have $93,000 in a pre-tax rollover IRA and make a $7,500 nondeductible contribution before converting that $7,500, your total balance is $100,500 and the after-tax portion is $7,500. The nontaxable ratio is $7,500 ÷ $100,500 = 7.46%, so only $560 of the conversion is tax-free and the remaining $6,940 is taxable as ordinary income.9Internal Revenue Service. Publication 590-B, Distributions from Individual Retirement Arrangements (IRAs) The strategy works cleanly only when your total traditional IRA balance is zero before the conversion. The conversion itself is reported on Form 8606, which walks through the ratio line by line.