The Backdoor Roth IRA, and the One Rule That Keeps It Clean
If you earn above roughly $168,000 single or $252,000 married filing jointly (2026 limits), the IRS won’t let you contribute directly to a Roth IRA. The phase-out is a line in the sand, and if you’re over it, the door is closed.
Except it isn’t. There’s a perfectly legal workaround called the backdoor Roth IRA, and the mechanic is simple. The problem is that most articles about it lead with scary warnings about paperwork, Form 8606, basis tracking, recordkeeping for decades, which isn’t quite wrong, but misses the point. The real rule is simpler: don’t let a Traditional IRA balance sit while you’re doing this. If you do it cleanly, the paperwork side is a formality.
This piece is about how to do it cleanly, and what happens when people don’t.
The mechanic
Three steps:
- Contribute to a Traditional IRA, non-deductibly. You can put in up to $7,500 a year (2026 limit), or $8,600 if you’re 50 or older. Because your income is over the direct-Roth limit, you’re also over the deductible-Traditional-IRA limit, so this contribution is “non-deductible.” You don’t take a tax break for it.
- Convert the Traditional IRA to a Roth IRA. Most custodians let you do this with a single form. Many people do it the same day, or within a week. Keep the window short.
- File Form 8606 with your tax return that year. It reports the non-deductible contribution (Part I) and the conversion (Part II). In a clean year, your basis nets to zero by year-end. There’s nothing to track going forward.
That’s it. The money is now in a Roth. It grows tax-free. Qualified withdrawals in retirement are tax-free. You’ve walked through the back door.
The one rule
First, be clear about what the IRS actually requires here: nothing. Anyone can do a Roth conversion, any day of the year, with any IRA balance. The IRS will not stop you. It will simply tax you. The real question in every conversion is: do you want to pay taxes, or don’t you?
Our rule exists to make the answer no:
Do the conversion whenever you like; same day as the contribution is fine. But by December 31 of that year, the combined balance of all your Traditional IRAs, SEP-IRAs, and SIMPLE IRAs should be zero, or as close to zero as you can get. December 31 is not when you act. It is when the IRS takes its snapshot.
That’s the whole thing. It is a hygiene rule, not a legal one, and it is the difference between a tax-free maneuver and a taxable one.
When that condition is met, the conversion is 100% after-tax dollars (no pre-tax money to mix with), no tax is owed, and there’s no residual basis to carry forward on Form 8606. You file the form that year, it records the mechanic, and the matter is closed.
When that condition isn’t met, the IRS applies the pro-rata rule and it gets expensive fast.
What goes wrong: the pro-rata rule
The pro-rata rule is a simple aggregation. The IRS looks at every Traditional IRA, SEP-IRA, and SIMPLE IRA you own, contributory, rollover, old, new, and treats them as a single pool. Your conversion is treated as a proportional slice of that pool.
Here’s the damage. Say you have $92,500 of pre-tax money in a rollover IRA from an old 401(k). You make a $7,500 non-deductible contribution to a separate Traditional IRA and convert that $7,500 to Roth. Aggregate Traditional IRA balance at year-end: $100,000, of which $7,500 is after-tax.
When you convert $7,500 to Roth, the IRS treats 7.5% of it as after-tax (the clean conversion you thought you were making) and 92.5% as a taxable distribution of pre-tax money. You owe ordinary income tax on roughly $6,938 you didn’t intend to convert. And the leftover after-tax basis that wasn’t used in the conversion is now stuck in the Traditional IRA: you’ll need Form 8606 for years to track it and hope the recordkeeping survives every job change, CPA change, and move.
One contributory IRA with fresh after-tax money. One rollover IRA with old pre-tax money. The IRS doesn’t care that they’re different accounts. They’re aggregated.
Contributory vs. rollover, a useful distinction, if only in your head
As a client-education framework, it helps to keep two categories straight:
- A rollover IRA holds money that came out of a 401(k) or other employer plan. Every dollar in it is pre-tax. Every dollar coming out will be fully taxable.
- A contributory IRA is one you contributed to directly. If the contribution was non-deductible, that portion has basis, and only the earnings on it are taxable.
The IRS aggregates them anyway for pro-rata purposes. But thinking about them as separate buckets helps clarify the problem: rollover balances are the enemy of a clean backdoor Roth. They’re the pre-tax denominator that pro-rata uses to tax your conversion.
How to clean up if you have a balance
If you’ve got a pre-tax Traditional or rollover IRA balance and you want to start doing backdoor Roths, you have two clean options:
1. Roll the pre-tax balance into a 401(k). Employer 401(k) plans, including Solo 401(k)s for the self-employed, are excluded from the pro-rata calculation. If your current 401(k) accepts incoming rollovers (most do), move the pre-tax money there. Your aggregate Traditional IRA balance goes to zero, and you’re free to run clean backdoors.
2. Convert the whole pre-tax balance to Roth. This triggers a tax bill, you pay ordinary income tax on every dollar converted, but it cleans the slate permanently. In a low-income year (early retirement, a sabbatical, a business loss), this can be the right move. Pay the tax once, and every future backdoor contribution converts tax-free.
Most of our clients who end up doing backdoor Roths either never had a pre-tax IRA balance to begin with, or they used the 401(k) rollover strategy to empty out what they had. Some used a mix, rolling what they could and converting the rest during a low-tax-bracket year.
What Form 8606 actually does (and why you shouldn’t fear it)
Form 8606 reports three things: non-deductible contributions, Roth conversions, and distributions from IRAs that contain basis. It’s the IRS’s way of tracking which of your IRA dollars have already been taxed, so you don’t pay tax on them twice.
In a clean backdoor year, the form is straightforward. You report the non-deductible contribution, the matching conversion, and your ending basis is $0. Next year, if you do another clean backdoor, you do it again. Each year stands on its own. Nothing carries forward.
Where 8606 becomes a multi-year tracking problem is when you contribute non-deductibly and don’t convert, or convert only partially, and residual basis accumulates in the account. Then you’re tracking a basis number across years, across CPAs, across custodians, for potentially decades. That’s the horror story most articles lead with. But it’s avoidable. The way to avoid it is the one rule: keep the Dec 31 aggregate Traditional IRA balance at zero.
If you’ve been doing backdoor Roths for years without filing Form 8606, it’s not the end of the world, the form can be filed retroactively for prior years. Start with your CPA, or call us.
Who this is for
The backdoor Roth is not a trick or a loophole. It’s a straight application of the tax code, used routinely by accountants and advisors. The ideal candidate is specific: someone whose income is above the direct Roth limit, who has no pre-tax IRA balance sitting anywhere (or is willing to move it into a 401(k) first), and who wants Roth exposure without adding a dollar to their tax bill. No balance means no pro-rata denominator: no basis to track, no tax owed, nothing to carry forward. That profile covers a lot of the successful self-employed professionals on Cape Cod: consultants, trades owners, professional service providers, anyone whose 1099 income has grown past the phase-out.
It’s especially powerful for the self-employed client who is also running a Solo 401(k). The Solo 401(k) is the destination for any pre-tax IRA money that would otherwise trip the pro-rata rule. The two strategies work together: the Solo 401(k) absorbs the pre-tax balances, the Traditional IRA stays clean, the backdoor stays clean, and the Roth grows tax-free.
The bottom line
One rule: don’t let a pre-tax Traditional, SEP, or SIMPLE IRA balance sit while you’re running backdoor Roths. If it’s zero on December 31, the conversion is tax-free, the 8606 is a formality, and there’s nothing to track.
The mechanic is simple. Keeping the account clean is the whole game.
If your IRA situation is messier than the clean case, that is normal, and it is usually fixable. The consultation is a conversation, not a sales call.
This article reflects the views of Long Point Wealth Management as of the date written. It is intended for educational purposes and should not be construed as personalized tax, legal, or investment advice. Tax rules governing IRA conversions and the pro-rata rule are subject to change; consult a qualified tax professional before implementing any strategy discussed.