Why Does Account Type Matter as Much as Account Balance in Retirement?
If you have one to two million dollars saved for retirement, you could still end up paying thousands more in taxes than you expect. Not because you didn't save enough. Because of where the money is sitting.
That one detail can raise your tax bill, spike your Medicare premiums, and pull more of your Social Security benefits into taxable income. Most people don't realize it until it's already happening. In this video, we walk through exactly why that happens and what you can do about it before retirement arrives.
This topic connects directly to how you structure withdrawals in retirement. You may also find our video on the retirement tax mistake most people miss helpful for a broader look at how tax-deferred savings create problems down the road.
The Three Tax Buckets Every Retirement Saver Needs to Understand
There are three types of accounts, each with a completely different tax treatment. How your retirement savings are distributed across these three buckets determines how much flexibility you have over your tax picture in retirement.
Bucket One: Pre-Tax Accounts
Traditional 401(k)s, IRAs, and 403(b)s. Every dollar that went in pre-tax was a deferral, not a permanent tax break. The IRS has been a silent partner from day one. Every dollar coming out in retirement is taxed as ordinary income. And once you reach a certain age, the IRS requires mandatory withdrawals called required minimum distributions, generally starting at age 73 though the starting age depends on birth year. Whether you need the money or not, you're required to take it and pay tax on it.
Bucket Two: Tax-Free Accounts
Roth IRAs and Roth 401(k)s. Growth and qualified withdrawals are generally income-tax-free. There are no required minimum distributions on Roth IRAs. And critically, Roth withdrawals don't count toward the income thresholds that trigger Medicare premium surcharges or increase the taxable portion of your Social Security benefits. That makes Roth accounts one of the most powerful tools available for managing retirement income.
Bucket Three: Taxable Brokerage Accounts
Taxable brokerage accounts are taxed along the way, but at capital gains rates, which are significantly lower than ordinary income tax rates. There are no forced withdrawals. For many retirees, a taxable brokerage account becomes the flexible bridge account that allows income management without triggering the thresholds that affect Medicare and Social Security taxation.
What Happens When Almost Everything Is in Bucket One
This is the situation most retirement savers are actually in. They saved consistently, did everything their employer plan offered, and ended up with most of their wealth concentrated in pre-tax accounts.
Here is what that looks like in practice. Say you retire with $1.8 million, most of it in a traditional 401(k). You need $90,000 a year to cover your lifestyle. At a 24% effective rate, that $90,000 net lifestyle requires roughly $118,000 in gross withdrawals just to keep the lights on.
Then stack the rest of the picture. You're collecting Social Security, say $36,000 a year. Once combined income crosses $44,000 as a married couple, up to 85% of your Social Security benefit becomes taxable income. That's not an 85% tax rate. It means 85% of the benefit gets added to your taxable income. The thresholds that trigger this, by the way, haven't been adjusted since 1993.
Then comes Medicare. In 2026, once income crosses $109,000 as an individual or $218,000 for a married couple, Medicare Part B premiums jump from $202.90 to $284.10 per month at the first tier. It works as a cliff. One dollar over the threshold triggers the full surcharge.
How Tax Diversification Changes the Outcome
When assets are spread across all three buckets, you control the income picture instead of the IRS controlling it for you. In a given year you can pull from Roth accounts to keep combined income below the Social Security taxation threshold. Draw from the brokerage account at capital gains rates. And manage how much pre-tax income you recognize to stay below the Medicare IRMAA cliff.
That kind of flexibility doesn't happen by accident. It has to be built deliberately, and the window to build it is before retirement, not after.
For a deeper look at how Roth conversions fit into this strategy, see our video on how much is too much when converting to Roth before RMDs .
Two Important Considerations Before Acting
The right account mix depends on your current tax bracket versus your expected retirement rate. If you're in a high bracket today, some pre-tax contributions still make sense. This isn't all-or-nothing. It's a conversation about proportion and timing.
Roth conversions in your early 60s, before Medicare enrollment, can meaningfully reduce the pre-tax balance that generates required minimum distributions and income stacking later. But conversions create taxable income in the year you do them, so the sizing and timing has to be deliberate. Done poorly, a conversion can trigger the very Medicare surcharges and Social Security taxation you're trying to avoid.
If you're concerned about how IRA withdrawals can affect your Social Security benefits, see our video on why your Social Security may be taxed more than you expect .
Frequently Asked Questions About Retirement Account Tax Diversification
Why does account type matter in retirement, not just account balance?
Because different account types are taxed differently when you withdraw money. Traditional 401(k)s and IRAs are taxed as ordinary income when you take distributions. Roth IRAs and Roth 401(k)s allow generally income-tax-free qualified withdrawals. Taxable brokerage accounts are taxed at lower capital gains rates. If most of your savings are in pre-tax accounts, every dollar you take out in retirement is taxed as ordinary income, which can push you into higher brackets, increase the taxable portion of your Social Security benefits, and trigger Medicare premium surcharges. Having assets across all three types gives you flexibility to manage your tax picture each year.
What is tax diversification in retirement?
Tax diversification means having retirement assets spread across accounts with different tax treatments: pre-tax accounts like traditional IRAs and 401(k)s, tax-free accounts like Roth IRAs and Roth 401(k)s, and taxable brokerage accounts. When you have assets in all three, you can choose which bucket to draw from each year based on your tax situation. That flexibility lets you manage income to stay below key thresholds for Social Security taxation and Medicare premium surcharges, which can meaningfully reduce your overall tax burden throughout retirement.
How does a large traditional IRA or 401(k) create tax problems in retirement?
A large pre-tax account means every dollar you withdraw is taxed as ordinary income. That income stacks on top of Social Security, investment income, and any other sources. Once combined income crosses certain thresholds, up to 85% of your Social Security benefit becomes taxable income. Higher income also triggers Medicare premium surcharges through IRMAA, which operate as income cliffs where one dollar over the threshold triggers a full surcharge increase. And required minimum distributions, generally starting at age 73 though the starting age depends on birth year, force withdrawals whether you need the money or not, which can compound these effects in later retirement years.
What are required minimum distributions and when do they start?
Required minimum distributions are mandatory annual withdrawals the IRS requires from traditional IRAs, 401(k)s, and most other pre-tax retirement accounts once you reach a certain age. Under current law, the starting age is generally 73, though the starting age depends on birth year under SECURE 2.0 rules, with the age phasing to 75 for younger retirees. The amount you must withdraw is calculated based on your account balance and life expectancy tables. Missing an RMD carries significant penalties. Because RMDs are taxed as ordinary income, a large pre-tax balance can generate substantial required income in later retirement years regardless of whether you need or want that money.
What is IRMAA and how does it affect Medicare premiums?
IRMAA stands for Income-Related Monthly Adjustment Amount. It is a Medicare premium surcharge applied to higher-income individuals and couples. Medicare Part B and Part D premiums are income-based, and once your modified adjusted gross income exceeds certain thresholds, premiums jump significantly. In 2026, the threshold is $109,000 for individuals and $218,000 for married couples filing jointly. IRMAA operates as a cliff, meaning one dollar over the threshold triggers a full surcharge increase rather than a gradual adjustment. Large IRA withdrawals, Roth conversions, or required minimum distributions can push income over these thresholds unexpectedly.
How do Roth conversions help with retirement tax planning?
A Roth conversion moves money from a traditional pre-tax account into a Roth IRA. You pay income tax on the converted amount in the year of conversion, and from that point the money grows tax-free and qualified withdrawals are generally income-tax-free. Done in lower-income years, typically in your early 60s before Social Security, Medicare, and required minimum distributions all start simultaneously, conversions can reduce the pre-tax balance that generates forced income later. The timing and sizing of conversions matters significantly. Converting too aggressively can trigger the very Medicare surcharges and Social Security taxation you're trying to avoid. Done carefully, conversions are one of the most effective tools for building long-term tax flexibility.
How much of Social Security can be taxed?
Up to 85% of your Social Security benefits can be subject to federal income tax depending on your combined income. The IRS uses a formula called provisional income to calculate how much is taxable. For married couples filing jointly, once combined income exceeds $44,000, up to 85% of the benefit is included in taxable income. These thresholds have not been adjusted for inflation since 1993, which means more retirees are affected each year. Managing income from pre-tax accounts, Roth accounts, and taxable accounts strategically can help keep more of your Social Security benefit out of the taxable calculation.
When is the right time to start building tax diversification for retirement?
The best time is well before retirement, ideally 10 or more years out, while you still have flexibility to direct contributions into different account types, do Roth conversions in favorable tax years, and build taxable brokerage assets alongside pre-tax accounts. The window to make meaningful changes narrows as required minimum distributions approach and income sources become less flexible. That said, even five to ten years before retirement there are often significant planning opportunities available. The key is building the diversification before you need it, not after retirement forces the issue.
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Investment advice is offered through Bayntree Wealth Advisors, LLC, an SEC-registered investment adviser. Insurance and annuity products are offered separately through Bayntree Wealth Advisors. Bayntree does not provide, and no statement contained herein shall constitute, tax or legal advice. You should consult a tax or legal professional on any such matters. Opinions expressed herein are solely those of Bayntree Wealth Advisors. All content is for informational purposes only and is not intended to provide the basis for any financial decisions.
Bayntree Wealth Advisors is not affiliated with the U.S. government or any governmental agency, including the Social Security Administration.
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