Roth IRA Conversion

Traditional IRAs and 401(k)s are usually funded with pre-tax dollars: you got a deduction (or contributed before tax) going in, the money grows tax-deferred, and you pay ordinary income tax when you withdraw it in retirement. A Roth IRA is the opposite: you fund it with after-tax dollars, it grows tax-free, and qualified withdrawals are tax-free.

A conversion bridges the two. You take money out of the pre-tax side, pay income tax on it now, and move it into the Roth side. You are effectively choosing to pay the tax today rather than in retirement. The core question is simple even if the math is not: is your tax rate likely to be lower now than when you would otherwise withdraw the money later? If yes, paying now can come out ahead. For the difference between the two account types, see traditional versus Roth IRA.

The process happens at your IRA custodian and is more paperwork than trading.

• 1. Have the accounts. You need a pre-tax account to convert from (a traditional IRA, or an old 401(k) rolled into a traditional IRA) and a Roth IRA to convert into. You can open the Roth at the same custodian.
• 2. Choose the amount. You do not have to convert everything. Many people convert a measured amount each year rather than a large lump sum, to control the tax hit.
• 3. Request the conversion. Tell the custodian to move the chosen amount from the traditional account to the Roth. This is a conversion, not a contribution, so it is not limited by the annual contribution cap.
• 4. Plan for the tax. The converted amount is added to your taxable income for the year. Ideally you pay that tax from outside cash rather than from the converted money, so the full balance keeps compounding in the Roth. You may owe estimated taxes.
• 5. Track the clocks. Note the conversion year, because each conversion starts its own 5-year clock for penalty-free access to that money.

Because a conversion cannot be reversed, the sizing decision in step 2 is the one worth slowing down on.

The whole cost of a conversion is the income tax you pay on the converted amount. There is no separate conversion tax and no early-withdrawal penalty on the conversion itself. The converted dollars simply stack on top of your other income for the year and are taxed at your ordinary rates.

• Fill a bracket, do not overflow it. A common approach is to convert only enough to reach the top of your current tax bracket, so none of the conversion is taxed at the next rate up.
• Pay the tax from outside the IRA. Using taxable savings to cover the bill keeps the full converted amount growing in the Roth. Paying the tax out of the IRA shrinks the balance and, before 59 and a half, can trigger a penalty on the portion used.
• Watch the ripple effects. A large conversion raises your reported income, which can affect Medicare premiums (IRMAA), tax credits, and other income-based thresholds. This is where a tax professional earns their keep.

Because the amount is added to income, running the numbers with tax software or a professional before converting is the safe move.

The pro-rata rule is the most common source of surprise tax bills. If you hold a mix of pre-tax and after-tax (nondeductible) money across your traditional, SEP, and SIMPLE IRAs, the IRS does not let you convert only the after-tax dollars tax-free. It treats every conversion as coming proportionally from all of them combined.

For example, if 90 percent of your total IRA balances is pre-tax and 10 percent is after-tax, then 90 percent of any amount you convert is taxable, no matter which dollars you think you are moving. This is exactly why a backdoor Roth gets complicated for someone who already has a large pre-tax IRA. The pro-rata math is unforgiving, so confirm it with a tax professional before converting.

Roth accounts have more than one 5-year rule, and the one that applies to conversions is often misunderstood. Each conversion starts its own five-year clock. To withdraw a converted amount without the 10 percent early penalty, you generally have to wait five years from January 1 of the year you converted, unless you are already 59 and a half or older.

This is separate from the 5-year rule governing tax-free access to earnings on regular Roth contributions. The practical takeaway: converted money is not meant to be tapped right away, and if you convert in several years, each batch has its own clock. Because the details matter, verify your specific timing with a tax professional before withdrawing converted funds early.

A backdoor Roth is a specific application of the conversion mechanic. High earners can be shut out of contributing to a Roth directly because of income limits. The workaround is to make a nondeductible contribution to a traditional IRA (which has no income limit) and then convert that contribution to a Roth.

Mechanically it is the same conversion, just applied to a small, freshly contributed after-tax amount rather than a large pre-tax balance. The catch is the pro-rata rule above: if you also hold pre-tax IRA money, the conversion will not be tax-free. Our backdoor Roth explained guide walks through the steps and the pro-rata trap in detail. As always, this is tax-sensitive, so a tax professional should confirm it works cleanly for you.

A conversion is a bet that paying tax now is cheaper than paying it later. The table below sketches the common situations, but every one of them depends on your full tax picture, so treat it as a starting point for a conversation with a tax professional, not a rule.

The pattern is consistent: conversions favor people with a low tax rate now, an expectation of higher rates later, a long runway, and cash on hand to pay the bill. They work against people converting in a peak-earning year or leaning on the IRA to fund the tax. None of this is one-size-fits-all.

The conversion itself is easy; the errors are usually in the planning around it.

• Converting too much in one year and pushing income into a higher bracket or above an income threshold that raises Medicare premiums or cuts a credit.
• Paying the tax from the IRA, which shrinks the balance and can trigger a penalty on the portion used before 59 and a half.
• Ignoring the pro-rata rule and expecting a tax-free conversion when a large pre-tax IRA makes most of it taxable.
• Forgetting the 5-year clock and withdrawing converted money too early, triggering a penalty.
• Assuming it can be undone. Recharacterizing a conversion is no longer allowed, so the decision is permanent.
• Doing it without running the numbers. Because the amount is added to income, guessing at the tax is how a conversion becomes a surprise.

A Roth conversion is a tax decision made at your IRA custodian, and Walnut does not perform conversions or advise on the tax. Where Walnut is useful is the investing side: once money is in a Roth or a traditional account, you can connect your real broker and see how the holdings inside those accounts are doing, build a thematic basket, and place trades you approve yourself. If you are still mapping out the account types, read Roth IRA explained and traditional versus Roth IRA. Walnut is not an investment adviser and not a tax adviser, and it does not tell you whether to convert.