To understand why the Backdoor Roth is necessary, we must first look at the "Front Door"—the direct contribution method. The IRS uses a metric called Modified Adjusted Gross Income (MAGI) to determine who is eligible to contribute directly to a Roth IRA. As your income rises, your ability to contribute "phases out" until it reaches zero .

Understanding Modified Adjusted Gross Income (MAGI)

MAGI is the gatekeeper of the Roth IRA. It is not simply your salary; it is your Adjusted Gross Income (AGI) with certain deductions added back in (like student loan interest or half of your self-employment tax). For most people, MAGI is very close to their total income, but for those on the edge of the limits, calculating it precisely is vital .

2025 and 2026 Income Thresholds

The IRS adjusts these limits annually for inflation. If your MAGI falls below the "Phase-out starts" level, you can contribute the full amount directly. If it falls within the "Phase-out range," you can only contribute a partial amount. If it is above the "Phase-out ends" level, you are completely barred from direct contributions .

2025 Contribution Limits and Phase-Outs

For the 2025 tax year, the maximum contribution is $7,000 ($8,000 if you are age 50 or older) .

Filing Status	Full Contribution If MAGI Is...	Partial Contribution (Phase-out)	No Direct Contribution If MAGI Is...
Single / Head of Household	Under $150,000	$150,000 – $165,000	$165,000 or more
Married Filing Jointly	Under $236,000	$236,000 – $246,000	$246,000 or more
Married Filing Separately	N/A	$0 – $10,000	$10,000 or more

2026 Contribution Limits and Phase-Outs

For the 2026 tax year, the limits increase slightly. The maximum contribution is $7,500 ($8,600 if you are age 50 or older) .

Filing Status	Full Contribution If MAGI Is...	Partial Contribution (Phase-out)	No Direct Contribution If MAGI Is...
Single / Head of Household	Under $153,000	$153,000 – $168,000	$168,000 or more
Married Filing Jointly	Under $242,000	$242,000 – $252,000	$252,000 or more
Married Filing Separately	N/A	$0 – $10,000	$10,000 or more

The "Married Filing Separately" Trap

One of the most restrictive rules in the tax code applies to married couples who live together but file separate tax returns. For these individuals, the phase-out starts at $0 and ends at $10,000 . This means that almost any married person filing separately who lives with their spouse is immediately disqualified from direct Roth contributions. For this group, the Backdoor Roth isn't just a high-earner strategy; it's often the only way to access a Roth IRA at all.

Why High Earners Are Targeted

The logic behind these limits is rooted in social policy. The Roth IRA was designed to help middle- and lower-income Americans save for retirement by providing a tax-free incentive. The government decided that high earners already have enough tax advantages (like the ability to save large amounts in 401(k)s) and therefore do not "need" the extra help of a Roth IRA. However, the Backdoor Roth strategy effectively renders these income limits optional for those who know how to navigate the rules .

Case Study: The "Almost Eligible" Couple

Consider Sarah and Mark, a married couple filing jointly. In 2025, their combined MAGI is $240,000.

The Problem: They are in the phase-out range ($236,000 to $246,000).
The Result: They can only contribute a small fraction of the $7,000 limit directly to a Roth IRA.
The Solution: Instead of doing the complex math to figure out their "partial" contribution, they can simply contribute the full $7,000 each to Traditional IRAs and then convert them. The Backdoor Roth removes the guesswork and allows them to hit the maximum limit regardless of their exact income .

The Spousal IRA Exception

It is a common misconception that you need your own high income to do a Backdoor Roth. If one spouse works and earns a high income while the other spouse does not work, the non-working spouse can still perform a Backdoor Roth IRA . This is known as a "Spousal IRA." As long as the total household income is enough to cover the contributions, both spouses can utilize the backdoor strategy to put a combined $14,000 (in 2025) or $15,000 (in 2026) into tax-free accounts .

Summary of the Barrier

The "Front Door" is guarded by MAGI limits that change every year. For anyone earning a six-figure salary, these limits are a constant hurdle. The Backdoor Roth is the solution to this hurdle, but it requires moving from a simple "deposit" mindset to a "process" mindset. In the next section, we will break down that process step-by-step.